Magnetic cell and magnetic memory

ABSTRACT

A magnetic cell comprises: a first ferromagnetic layer whose magnetization is substantially fixed in a first direction; a second ferromagnetic layer whose magnetization is substantially fixed in a second direction opposite to the first direction; a third ferromagnetic layer provided between the first and the second ferromagnetic layers, a direction of magnetization of the third ferromagnetic layer being variable; a first intermediate layer provided between the first and the third ferromagnetic layers; and a second intermediate layer provided between the second and the third ferromagnetic layers. The direction of magnetization of the third ferromagnetic layer can be determined under an influence of spin-polarized electrons upon the third ferromagnetic layer by passing a current between the first and the second ferromagnetic layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2002-342447, filed on Nov. 26,2002; the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a magnetic cell and a magnetic memory,and more particularly, it relates to a magnetic cell and a magneticmemory which can be written-in by passing spin-polarized electrons.

Conventionally, in order to control the direction of magnetization of amagnetic material, the method of applying a magnetic field to themagnetic material has been taken. For example, in the case of the harddisk drive, writing-in is carried out by reversing the magnetizationdirection of a medium by applying a magnetic field generated from arecording head. Moreover, in a solid-state magnetic memory, themagnetization direction of a cell is controlled by applying acurrent-induced magnetic field generated by passing a current to thewirings provided near the magnetoresistance effect elements includingthe cell. The magnetization direction control by the external magneticfields has old history, and can be taken as an established technology.

On the other hand, in the recent progress of the nanotechnology, theminiaturization of the magnetic substance has been carried out rapidly,and it has been required to perform the magnetization control withnano-scale and locally. However, since the magnetic field fundamentallyhas the character to spread over a space, it is difficult to be madelocalized. As the size of a recording bit or a cell becomes minute, whenselecting a specific recording bit or a specific cell and controllingthe magnetization direction, the problem of a “cross talk” that amagnetic field reaches to a next bit or a next cell becomes remarkable.Moreover, if a generation source of the magnetic field is made small forthe sake of making the magnetic field localized, the problem that thegenerating magnetic field can not be obtained enough will arise.

Recently, “Direct-current-driving magnetization reversal” in which themagnetization reversal is carried out by passing a current to a magneticmaterial is disclosed by F. J. Albert, et al., Appl. Phy. Lett. 77, 3809(2000).

The magnetization reversal by a current is the phenomenon that theangular momentum of the spin-polarized electrons generated when thespin-polarized current passes magnetic layers cause reversal ofmagnetization by transmitting and acting on the angular momentum of themagnetic material whose magnetization is to be reversed. By using thisphenomenon, it becomes possible to act on the magnetic material withnano-scale and also to record to a minuter magnetic material.

However, currently, there is a problem that the reversal currentrequired to reverse a magnetization is as large as 10 mA through severalmA when the size of a cell is in a range between 100 nm and several 10nm. That is, the magnetic cell structure where required current for themagnetization reversal is as small as possible is required in order toprevent a destruction of the element by the current, and to prevent ageneration of heat and to reduce power consumption.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided a magneticcell comprising: a first ferromagnetic layer whose magnetization issubstantially fixed in a first direction; a second ferromagnetic layerwhose magnetization is substantially fixed in a second directionopposite to the first direction; a third ferromagnetic layer providedbetween the first and the second ferromagnetic layers, a direction ofmagnetization of the third ferromagnetic layer being variable; a firstintermediate layer provided between the first and the thirdferromagnetic layers; and a second intermediate layer provided betweenthe second and the third ferromagnetic layers,

-   -   the direction of magnetization of the third ferromagnetic layer        being determined under an influence of spin-polarized electrons        upon the third ferromagnetic layer by passing a current between        the first and the second ferromagnetic layers.

According to other aspect of the invention, there is provided a magneticcell comprising: a first magnetically fixed part including a firstferromagnetic layer whose magnetization is substantially fixed in afirst direction; a second magnetically fixed part including a secondferromagnetic layer whose magnetization is substantially fixed in asecond direction opposite to the first direction; a third ferromagneticlayer provided between the first and the second magnetically fixed part,a direction of magnetization of the third ferromagnetic layer beingvariable; a first intermediate layer provided between the firstmagnetically fixed part and the third ferromagnetic layer; and a secondintermediate layer provided between the second magnetically fixed partand the third ferromagnetic layer,

-   -   an easy axis of magnetization of the third ferromagnetic layer        being substantially in parallel to the first direction,    -   at least one of the first and the second magnetically fixed        parts including a laminated structure where ferromagnetic layers        and at least one nonmagnetic layer are laminated in turn and the        ferromagnetic layers are antiferromagnetically coupled via the        nonmagnetic layer,    -   the first ferromagnetic layer adjoining the first intermediate        layer,    -   the second ferromagnetic layer adjoining the second intermediate        layer, and    -   the direction of magnetization of the third ferromagnetic layer        being determined under an influence of spin-polarized electrons        upon the third ferromagnetic layer by passing a current between        the first and the second magnetically fixed parts.

According to other aspect of the invention, there is provided a magneticmemory comprising a memory cell where a plurality of magnetic cells arearranged in a matrix fashion, each of the magnetic cells being separatedby an insulator from other memory cells, each of the magnetic cellshaving: a first ferromagnetic layer whose magnetization is substantiallyfixed in a first direction; a second ferromagnetic layer whosemagnetization is substantially fixed in a second direction opposite tothe first direction; a third ferromagnetic layer provided between thefirst and the second ferromagnetic layers, a direction of magnetizationof the third ferromagnetic layer being variable; a first intermediatelayer provided between the first and the third ferromagnetic layers; anda second intermediate layer provided between the second and the thirdferromagnetic layers, the direction of magnetization of the thirdferromagnetic layer being determined under an influence ofspin-polarized electrons upon the third ferromagnetic layer by passing acurrent between the first and the second ferromagnetic layers.

According to other aspect of the invention, there is provided a magneticmemory comprising a memory cell where a plurality of magnetic cells arearranged in a matrix fashion, each of the magnetic cells being separatedby an insulator from other memory cells, each of the magnetic cellshaving: a first magnetically fixed part including a first ferromagneticlayer whose magnetization is substantially fixed in a first direction; asecond magnetically fixed part including a second ferromagnetic layerwhose magnetization is substantially fixed in a second directionopposite to the first direction; a third ferromagnetic layer providedbetween the first and the second magnetically fixed part, a direction ofmagnetization of the third ferromagnetic layer being variable; a firstintermediate layer provided between the first magnetically fixed partand the third ferromagnetic layer; and a second intermediate layerprovided between the second magnetically fixed part and the thirdferromagnetic layer,

-   -   an easy axis of magnetization of the third ferromagnetic layer        being substantially in parallel to the first direction,    -   at least one of the first and the second magnetically fixed        parts including a laminated structure where ferromagnetic layers        and at least one nonmagnetic layer are laminated in turn and the        ferromagnetic layers are antiferromagnetically coupled via the        nonmagnetic layer,    -   the first ferromagnetic layer adjoining the first intermediate        layer,    -   the second ferromagnetic layer adjoining the second intermediate        layer, and    -   the direction of magnetization of the third ferromagnetic layer        being determined under an influence of spin-polarized electrons        upon the third ferromagnetic layer by passing a current between        the first and the second magnetically fixed parts.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription given here below and from the accompanying drawings of theembodiments of the invention. However, the drawings are not intended toimply limitation of the invention to a specific embodiment, but are forexplanation and understanding only.

In the drawings:

FIG. 1 is a schematic diagram which illustrates a fundamentalcross-sectional structure of a magnetic cell according to the firstembodiment of the present invention;

FIG. 2 is a schematic diagram showing a cross-sectional structure of themagnetic cell in which the magnetization is made to be perpendicular tothe film plane;

FIG. 3A and FIG. 3B show schematic section views for explaining themechanism of the “writing” of the magnetic cell expressed in FIG. 1;

FIG. 4A and FIG. 4B show schematic section views for explaining themechanism of “writing” in case of a reverse type magnetoresistanceeffect of a magnetic cell;

FIG. 5A and FIG. 5B show schematic section views for explaining themechanism of the “writing” in the magnetic cell expressed in FIG. 2;

FIG. 6 is a schematic diagram for explaining the mechanism of thereading the magnetic cell of this embodiment;

FIG. 7A and FIG. 7B are schematic diagrams for explaining the change ofthe magnetoresistance by the change of the relative direction of themagnetization;

FIG. 8 shows a schematic section view showing the first example of theasymmetrical structure;

FIG. 9A shows a schematic section view showing the second example of theasymmetrical structure;

FIG. 9B shows a schematic section view showing the third example of theasymmetrical structure;

FIG. 10 shows a schematic section view showing the fourth example of theasymmetrical structure;

FIG. 11 shows a schematic section view showing the fifth example of theasymmetrical structure;

FIG. 12 shows a schematic section view showing the magnetostaticcoupling between the magnetically fixed layers C1 and C2;

FIG. 13 shows a schematic section view showing the magnetic cellprovided the antiferromagnetic layer;

FIG. 14 shows a schematic section view showing the magnetic cell wherethe magnetizations of the magnetically fixed layers C1 and C2 are fixedby the antiferromagnetic layer, respectively;

FIG. 15 shows a schematic section view showing the magnetic cell wherethe magnetizations of the magnetically fixed layers C1 and C2 are fixedby the antiferromagnetic layer, respectively;

FIG. 16 shows a schematic section view showing another example of themagnetic cell where the magnetizations of the magnetically fixed layersC1 and C2 are fixed by the antiferromagnetic layer, respectively;

FIG. 17 is a graphical representation showing the exchange interactionbetween two ferromagnetic layers through the non-magnetic layer on thenon-magnetic layer thickness;

FIG. 18 shows a schematic section view showing the magnetic cellprovided the two magnetic recording layers;

FIG. 19 shows a schematic section view showing an example where themagnetically fixed layer and the magnetic recording layer form thelaminated structures;

FIG. 20 shows a schematic section view showing an example where themagnetically fixed layer and the magnetic recording layer form thelaminated structures, respectively;

FIG. 21 shows a schematic section view showing an example where themagnetically fixed layer and the magnetic recording layer form thelaminated structures, respectively;

FIG. 22 shows a schematic section view showing the example in which twomagnetically fixed structures are provided;

FIG. 23 shows a schematic section view showing an example where themagnetic recording layer is also the laminated structure in addition tothe two magnetically fixed structures;

FIG. 24 shows also a schematic section view showing an example where themagnetic recording layer is the laminated structure in addition to thetwo magnetically fixed structures;

FIG. 25 shows a schematic section view showing an example where themagnetic recording layer is the laminated structure in addition to thetwo magnetically fixed structures;

FIG. 26 is a schematic diagram showing the magnetic memory using themagnetic cells of the invention;

FIG. 27 is a schematic diagram showing a structure in which the cells 10share the layers of their cells;

FIG. 28 shows a schematic section view showing the second example of themagnetic memory using the magnetic cells of the invention;

FIG. 29A is a schematic diagram showing the principal part sectionstructure of the magnetic cell of this example;

FIG. 29B is a schematic diagram showing the principal part sectionstructure of the magnetic cell of the comparative example;

FIG. 30 is a schematic diagram showing the probing in the fifth example;

FIG. 31 is a schematic diagram showing the magnetic memory in the sixthexample of the invention;

FIG. 32 is a graphical representation showing the differentialresistance of the sample A10;

FIG. 33 is a graphical representation showing the differentialresistance of the sample B10;

FIG. 34 is a graphical representation showing differential resistancechange which removed the curvilinear component of the background inFIGS. 32 and 33, and was further normalized by differential resistanceof a low resistance state;

FIG. 35 is a graphical representation showing the relation between theaverage value of the critical magnetization reversal current Ic, andcell size;

FIG. 36 is a schematic diagram showing the cross-sectional structure ofthe sample C20;

FIG. 37 is the graphical representation which expresses the dependenceof the differential resistivity change on the current about the samplesA20, B20, D20, and E20 with the size 60 nm×110 nm;

FIG. 38 is a graphical representation showing the relation between theaverage value of critical current Ic and cell size;

FIG. 39 is the graphical representation which expresses the relationbetween the differential resistivity change and the current about thesamples A30, B30, D30, and E30;

FIG. 40 is a graphical representation showing the relation between theaverage value of critical current Ic and cell size;

FIG. 41 is the graphical representation which expresses the relationbetween the differential resistivity change and the current about thesamples A40, B40, D40, and E40;

FIG. 42 is a graphical representation showing the relation between theaverage value of critical current Ic and cell size;

FIG. 43 is the graphical representation which expresses the relationbetween the differential resistivity change and the current about thesamples A50, B50, C50, and D50;

FIG. 44 is a graphical representation showing the relation between theaverage value of critical current Ic and cell size;

FIG. 45 is a schematic diagram showing the cross-sectional structure ofthe sample D60 and H60 in the thirteenth example of the invention;

FIG. 46 is a schematic diagram showing the cross-sectional structure ofthe magnetic cell made in the example of the invention;

FIG. 47 is a schematic diagram showing the cross-sectional structure ofthe magnetic cell of the comparative example;

FIG. 48 is a schematic diagram showing the cross-sectional structure ofthe magnetic cell which has the two magnetically fixed layers C1 and C2whose magnetizations are parallel;

FIGS. 49A through 49D are schematic diagrams showing the cross-sectionalstructures of the memory cells of the magnetic memories of the exampleof the invention;

FIG. 50 is the schematic diagram which expresses the structure in whichthe ion milling is stopped at the top of the Al₂O₃ layer of theintermediate-layer B2; and

FIG. 51 is a schematic diagram showing the magnetic memory using diodes.

DETAILED DESCRIPTION

Referring to drawings, some embodiments of the present invention willnow be described in detail.

FIG. 1 is a schematic diagram which illustrates a fundamentalcross-sectional structure of the magnetic cell according to the firstembodiment of the present invention. This magnetic cell has, twomagnetically fixed layers (pinned layer) C1 and C2 whose magnetizationdirections M1 and M2 are anti-parallel, a magnetic recording layer (freelayer) A whose magnetization direction can be changed, and intermediatelayers B1 and B2 between the magnetic recording layer A and themagnetically fixed layers.

The magnetization direction M of the magnetic recording layer A can becontrolled by passing current I between the upper magnetically fixedlayer C1 and the lower magnetically fixed layer C2. Specifically, themagnetization direction M of the magnetic recording layer A can bereversed by changing direction (polarity) of the flow of the current I.In recording information, “0” and “1” are assigned respectively,according to the magnetization direction M.

And, in the magnetic cell of the present invention, the magnetizationdirection of each layer may be not only parallel to a film plane butalso substantially perpendicular to a film plane. FIG. 2 is a schematicdiagram showing a cross-sectional structure of the magnetic cell inwhich the magnetization directions are made to be perpendicular to thefilm plane. In this magnetic cell, the magnetizations M, M1, and M2 aremade to be substantially perpendicular to the film plane. Also in thiscase, the magnetization direction M of the magnetic recording layer Acan be controlled by passing the current I between the upper pinnedlayer C1 and the lower pinned layer C2.

Next, the mechanism of the “writing” in the magnetic cell of theinvention will be explained.

FIG. 3A and FIG. 3B are schematic section views for explaining themechanism of the “writing-in” in the magnetic cell expressed in FIG. 1.The mechanism to write in the magnetic recording layer A by providingtwo magnetically fixed layers C1 and C2, and by passing the current Iacross these interfaces will be explained as follows. First, the casewhere both of the magnetoresistance effects through the intermediatelayer B1 and the magnetoresistance effects through the intermediatelayer B2 are of a normal type will be explained. Here, the “normal type”magnetoresistance effect corresponds to the case where the resistancebecomes higher when the magnetizations of the magnetic layers on bothsides of the intermediate layer are anti-parallel than that when theyare parallel.

That is, in the normal type, the resistance between the magneticallyfixed layers C1 and the magnetic recording layers A through theintermediate layer B1 becomes lower when the magnetization of themagnetically fixed layers C1 and the magnetization of the magneticrecording layers A are parallel than they are anti-parallel. Also, theresistance between the magnetically fixed layers C2 and the magneticrecording layers A through the intermediate layer B2 becomes lower whenthe magnetization of the magnetically fixed layers C2 and themagnetization of the magnetic recording layers A are parallel than theyare anti-parallel.

First, in FIG. 3A, the electron which passes the magnetically fixedlayer C1 which has magnetization M1 tends to have a spin of themagnetization direction M1. And, this electron flows to the magneticrecording layer A transmitting the angular momentum of the spin to themagnetic recording layer A, and acts on the magnetization M.

The magnetization M2 of the second magnetically fixed layer C2 is in thereverse direction to the magnetization M1. Therefore, the electron whichhas the spin of the same direction as the magnetization M1 (therightward direction in this figure) is reflected at the interfacebetween the second magnetically fixed layer C2 and the intermediatelayer B2. This reflected spin of the opposite direction to themagnetization of the second magnetically fixed layer C2 also acts on themagnetic recording layer A.

That is, since the spin electron which has the same magnetizationdirection as the first magnetically fixed layer acts on the magneticrecording layer A twice, a write-in action of twice as much can beobtained substantially. Consequently, the writing in the magneticrecording layer A can be carried out with current smaller than before.

FIG. 3B expresses the case where the current I is reversed. In thiscase, the electron constituting the current I tends to have the spinwith the same direction as the magnetization direction M2 (in theleftward direction in this figure) by the action of the magnetization M2of the second magnetically fixed layer C2. This spin electron acts onthe magnetization M of the magnetic recording layer A in the magneticrecording layer A. Then, the spin electron is reflected at the interfacebetween the first magnetically fixed layer C1 having the reversemagnetization M1 to the magnetization M of the magnetic recording layerA and the intermediate layer B1. Then, the electron acts on the magneticrecording layer A again.

In the above, the case where the magnetoresistance effects between themagnetically fixed layers C1 and C2 and the magnetic record A throughthe intermediate layer B1 and B2, are of the normal type were explained.

Next, the case where they are of a reverse type will be explained. FIG.4A and FIG. 4B are schematic section views for explaining the mechanismof “writing-in” in case of a reverse type magnetoresistance effect of amagnetic cell. That is, in the reverse type, the resistance between themagnetically fixed layers C1 and the magnetic recording layers A throughthe intermediate layer B1 becomes higher when the magnetization of themagnetically fixed layers C1 and the magnetization of the magneticrecording layers A are parallel than they are anti-parallel. And, theresistance between the magnetically fixed layers C2 and the magneticrecording layers A through the intermediate layer B2 becomes lower whenthe magnetization of the magnetically fixed layers C1 and themagnetization of the magnetic recording layers A are parallel than theyare anti-parallel.

When the magnetoresistance effects through the intermediate layers B1and B2 are of reverse type, the spin electron which acts on the magneticrecording layer A from the magnetically fixed layer C1 has the reversedirection to the spin electron of FIG. 3A, as expressed in FIG. 4A.Also, the spin electron which acts on the magnetic recording layer Afrom the magnetically fixed layer C2 has the reverse direction to thespin electron of FIG. 3A. Consequently, as expressed in FIG. 4A, themagnetization direction M of the magnetic recording layer A becomesanti-parallel to that of the magnetically fixed layer C1, and parallelto that of the magnetically fixed layer C2.

On the other hand, when the electron current is passed towards themagnetically fixed layer C1 from the magnetically fixed layer C2, themagnetization direction M of the magnetic recording layer A becomesparallel to that of the magnetically fixed layer C1. As explained above,when both of the magnetoresistance effects through the intermediatelayers B1 and B2 are of the normal type, or when both are of the reversetype, the magnetization direction M of the magnetic recording layer A isdetermined in response to the current direction.

However, when one of the magnetoresistance effects through theintermediate layers B1 and B2 is of the normal type and the other is ofthe reverse type, it is disadvantage for writing in the magneticrecording layer A because the degree of spin-polarization of theelectron flowing into the magnetic recording layer A becomes small.

For example, when the magnetoresistance effect between the magneticallyfixed layer C1 and the magnetic recording layer A through theintermediate layer B1 is of the normal type and the magnetoresistanceeffect between the magnetically fixed layer C2 and the magneticrecording layer A through the intermediate layer B2 is of the reversetype, the direction of a spin electron acting on the magnetic recordinglayer A from the intermediate layer B1 becomes different from that fromthe intermediate layer B2. So, in this case, the effect of the presentinvention can hardly be acquired.

As explained above, according to this embodiment, the directions of thespins acting on the magnetic recording layer A turn into the samedirections finally by making the magnetization M1 and M2 of the twomagnetically fixed layers anti-parallel, and a twice as much action isobtained. Consequently, it becomes possible to reduce the current forreversal of the magnetization of the magnetic recording layer A.

The same mechanism as the mechanism of the “writing-in” explained abovecan be said about the magnetic cell where the direction of themagnetization is controlled to be perpendicular to the film plane, asexpressed in FIG. 2.

FIG. 5A and FIG. 5B show schematic section views for explaining themechanism of the “writing-in” in the magnetic cell expressed in FIG. 2.The same symbols are given to the same elements as what were mentionedabove with reference to FIG. 1 through FIG. 4B about these figures, anddetailed explanation will be omitted.

As expressed in FIG. 5A and FIG. 5B, also when the magnetizationdirection is made to be perpendicular to the film plane, the directionsof the spins acting on the magnetic recording layer A turn into the samedirections finally by making the magnetizations M1 and M2 of twomagnetically fixed layers anti-parallel, and a twice as much action isobtained. As the result, it becomes possible to reduce the current forreversal of the magnetization of the magnetic recording layer A.

Next, the mechanism of “read-out” in the magnetic cell of thisembodiment will be explained. In the magnetic cell of this embodiment, adetection of the magnetization direction M of the magnetic recordinglayer A can be performed using the “magnetoresistance effect” where theresistance varies by relative direction of the magnetization of eachlayer.

FIG. 6 is a schematic diagram for explaining the mechanism of thereading out the magnetic cell of this embodiment. That is, when usingthe magnetoresistance effect, the sense current I is passed between oneof the magnetically fixed layers C1 and C2, and the magnetic recordinglayer, and the magnetoresistance is measured. Although the case wherethe magnetoresistance is measured between the first magnetically fixedlayer C1 and the magnetic recording layer A is illustrated in FIG. 6,the magnetoresistance may be measured between the second magneticallyfixed layer C2 and the magnetic recording layer A.

FIG. 7A and FIG. 7B are schematic diagrams for explaining the change ofthe magnetoresistance by the change of the relative direction of themagnetization.

FIG. 7A shows the case where the magnetization direction M1 of themagnetically fixed layer C1 and the magnetization direction M of themagnetic recording layer A are the same directions. In this case, themagnetoresistance detected by the sense current I passing through theselayers is relatively small in the normal type, and it is relativelylarge in the reverse type.

On the other hand, FIG. 7B shows the case where the magnetizationdirection M1 of the magnetically fixed layer C1 and the magnetizationdirection M of the magnetic recording layer A are anti-parallel. In thiscase, the magnetoresistance detected by the sense current I passedthrough these layers is relatively large in the normal type, and it isrelatively small in the reverse type. It becomes possible to carry outrecord read-out of the data with two values by assigning “0” and “1” tothese different resistances respectively.

On the other hand, there is a method of detecting the magnetoresistanceby passing the sense current through the both ends of the magnetic cell.That is, the magnetoresistance is detected by the sense current beingpassed between the first magnetically fixed layer C1 and the secondmagnetically fixed layer C2. However, in the present invention, a pairof the magnetizations M1 and M2 of the magnetically fixed layers C1 andC2 is anti-parallel and both of the magnetoresistance effects throughthe intermediate layers B1 and B2 are of the normal type or of thereverse type. Therefore, the magnetoresistance effect detected willbecome same values regardless of the magnetization direction M of themagnetic recording layer A, when “symmetrical structure on the magneticrecording layer A”, i.e. the quantities of the spin dependencescatterings of the magnetically fixed layers C1 and C2 are equal, or thedegrees of spin-polarized of the electron which acts on the magneticrecording layer from the magnetically fixed layers C1 and C2 are equal.Then, it is necessary to adopt “asymmetrical structure on the magneticrecording layer A.”

FIG. 8 is a schematic section view showing the first example of theasymmetrical structure.

As an example of the asymmetrical structure, the size of themagnetization M1 and M2 can be changed by differentiating thethicknesses, materials, etc. of the magnetically fixed layers C1 and C2.In the case of the example expressed in FIG. 8, the contribution of spindependent bulk scattering by the magnetically fixed layer C2 is madelarger than that by C1, by making the second magnetically fixed layer C2thicker than the first magnetically fixed layer C1. Then, when “reading”by passing the sense current between the magnetically fixed layers C1and C2 is carried out, the magnetoresistance effect detected varydepending on the direction of the magnetization M of the magneticrecording layer A.

However, the quantities of the spin dependence scatterings by themagnetically fixed layers C1 and C2 may be changed by changing materialsof the first and the second magnetically fixed layers C1 and C2 insteadof changing the thicknesses of those, as expressed in FIG. 8.

FIG. 9A shows a schematic section view showing the second example of theasymmetrical structure.

In the case of this example, the thicknesses of the intermediate layersB1 and B2 are different from each other. That is, the intermediate layerB1 is made to have the thickness with which the magnetoresistance effectis easy to be detected, and the other intermediate layer B2 is made tohave the thickness with which the magnetoresistance effect is hard to bedetected. In this case, it is desirable to make the thickness of theintermediate layer B1 in a range between 0.2 nm and 10 nm, and make thethickness of the intermediate layer B2 in a range between 3 nm and 50nm.

Then, the magnetoresistance effect between the magnetically fixed layerC1 and the magnetic recording layers A through the intermediate layer B1can mainly be detected, and it will become easy to detect themagnetization M of the magnetic recording layer A.

FIG. 9B shows a schematic section view showing the third example of theasymmetrical structure. In this example, the resistances of theintermediate layers B1 and B2 may be differentiated. In order todifferentiate the resistances, it is effective to differentiate thematerials and compositions of the intermediate layers B1 and B2 eachother, or to add elements to one of the intermediate layers.Furthermore, one of the intermediate layer B1 and B2 may be formed withelectric conduction material, such as copper (Cu), and the other may beformed with an insulator. If the intermediate layer B1 (or B2) is formedwith a thin insulator, the so-called tunneling magnetoresistance effect(TMR) will be obtained, and a big reproduction signal output can beobtained when the magnetization of the magnetic recording layer A isread out.

FIG. 10 shows a schematic section view showing the forth example of theasymmetrical structure.

In this example, the middle substance layer IE is inserted in theintermediate layer B2. This middle substance layer IE has a role ofincreasing the magnetoresistance effect. A discontinuous insulating thinfilm can be used as the middle substance layer IE, for example. That is,it becomes possible to increase the magnetoresistance effect byinserting the insulating thin film which has a pinhole etc. in theintermediate layer.

As such a discontinuous insulating thin film, an oxide or a nitride ofan alloy of nickel (Ni) and copper (Cu), the oxide or a nitride of analloy of nickel (Ni) and gold (Au), an oxide or a nitride of an alloy ofaluminum (Al) and copper (Cu), etc. can be used, for example.

A phase separation of the compounds, such as an oxide and a nitride ofthese alloys, is carried out by bringing them close to the equilibriumwith heating etc. That is, the compounds separate into a phase whoseresistance is low and which is hard to become compounds (oxidization,nitride, etc.), such as Au and Cu, and a phase whose resistance is highand which is easy to become compounds, such as Ni and Al. Therefore, thediscontinuous insulating thin film in which pinholes exist can be formedby controlling composition, temperature, or film deposition energy.Thus, the current pass can be narrowed, and the spin dependentscattering can be easily detected because of the higher resistance.Consequently, a big magnetoresistance effect is obtained.

By inserting such a middle substance layer IE in either of theintermediate layer B1 or B2, the magnetoresistance effect between themagnetically fixed layer and the magnetic recording layer which are onthe both sides of the middle substance layer IE increases, and becomeseasy to be detected.

FIG. 11 shows a schematic section view showing the fifth example ofasymmetrical structure.

That is, in this example, the intermediate-layer B2 is an insulatinglayer which has pinholes PH. The pinholes PH are embedded by thematerial of the magnetically fixed layer or the magnetic recording layerof the both sides.

Thus, by connecting the magnetically fixed layer C2 (or C1) and themagnetic recording layer A through the pinholes PH, the so-called“magnetic point contact” is formed and a very large magnetoresistanceeffect is obtained. Therefore, the direction of the magnetization M ofthe magnetic recording layer A can be easily found by detecting themagnetoresistance effect between the magnetic layers of the both sidesthrough these pinholes PH.

Here, it is desirable for the diameters of the openings of the pinholesPH to be less than about 20 nm. And, the shape of the pinholes PH can bevarious kinds of shape, such as a cone shape, cylindrical, a globularshape, the shape of multiple weights, and the shape of a multiplepillar. And, one or more pinholes PH may be exist. However, it isdesirable for the pinholes PH to

In the above, the example of the asymmetrical structure for reading thedirection of the magnetization of the recording layer A easily by themagnetoresistance effect was explained, referring to FIG. 7 through FIG.10. Such asymmetrical structures can be similarly applied to themagnetic cell with perpendicular magnetization type expressed in FIG. 2,and the same effect can be obtained.

Next, how to make the directions of the magnetizations M1 and M2 of twomagnetically fixed layers C1 and C2 be anti-parallel in the magneticcell of the invention will be explained.

First, the method of making the magnetizations M1 and M2 to beanti-parallel by carrying out magnetostatic coupling between themagnetically fixed layers C1 and C2 can be mentioned as a first method.

FIG. 12 shows a schematic section view showing the magnetostaticcoupling between the magnetically fixed layers C1 and C2. In the case ofthis example, the magnetic yokes MY are provided on the both sides ofthe magnetic cell through the insulating layers IL. The magnetic fieldsexpressed with the arrows are formed in the magnetic yokes MY, and theclosed loop magnetic domain through these magnetic yokes MY and themagnetically fixed layers C1 and C2 are formed. Thus, if themagnetostatic coupling between the magnetically fixed layers C1 and C2is carried out through the magnetic yokes MY, the magnetization M1 andthe magnetization M2 can be made to be anti-parallel by the closed loopmagnetic domain.

In this case, the directions of the magnetizations M1 and M2 of themagnetically fixed layers can be controlled by differentiating thethicknesses of two magnetically fixed layers C1 and C2, and applying anexternal pulse magnetic field.

Moreover, it becomes possible to control the direction of themagnetization of the magnetically fixed layer by forming anantiferromagnetic layer in contact with the outside of one magneticallyfixed layer and giving unidirectional anisotropy.

FIG. 13 is a schematic section view showing the magnetic cell providedthe antiferromagnetic layer. That is, the direction of the magnetizationM2 is fixed by the exchange coupling between the antiferromagnetic layerAF provided under the magnetically fixed layer C2 and the magneticallyfixed layer C2. And the magnetization M1 of the magnetically fixed layerC1 which forms a magnetostatic coupling with the magnetically fixedlayer C2 through the magnetic yokes MY serves as a reverse direction tothe magnetization M2.

Moreover, the magnetizations of the magnetically fixed layers C1 and C2may be fixed by antiferromagnetic layers, respectively.

FIG. 14 is a schematic section view showing the magnetic cell where themagnetizations of the magnetically fixed layers C1 and C2 are fixed bythe antiferromagnetic layers, respectively. That is, theantiferromagnetic layer AF1 is provided adjacent to the magneticallyfixed layer C1, and the antiferromagnetic layer AF2 is provided adjacentto the magnetically fixed layer C2. And the magnetizations M1 and M2 arefixed to be anti-parallel by the next antiferromagnetic layers AF1 andAF2, respectively.

Such structure can be easily formed by selecting materials of theantiferromagnetic layers AF1 and AF2 appropriately so that theirblocking temperatures of the antiferromagnetic layers AF1 and AF2 may bedifferent from each other. That is, after forming the laminatedstructure expressed in FIG. 14, the magnetic cell is heated beingapplied the magnetic field. After that, the magnetic cell is cooled.Then, the magnetization of the antiferromagnetic layer with a highblocking temperature is fixed. Then, the magnetic cell is cooledfurther, after reversing the magnetic field. Then, the magnetization ofthe other antiferromagnetic layer with a low blocking temperature isfixed to be anti-parallel.

FIG. 15 also shows a schematic section view showing the magnetic cellwhere the magnetizations of the magnetically fixed layers C1 and C2 arefixed by the antiferromagnetic layers, respectively. That is, in thisexample, the antiferromagnetic layer AF2 is provided the outside themagnetically fixed layer C2, and the magnetic layer FM and theantiferromagnetic layer AF 1 are provided outside the other magneticallyfixed layer C1 through the non-magnetic layer AC.

In this case, the non-magnetic layer AC is made to have a thickness withwhich the magnetically fixed layer C1 and the magnetic layer FM areantiferromagnetically exchange coupled. And, ruthenium (Ru), copper(Cu), etc. can be used as a material of the non-magnetic layer AC.

According to the usual process of giving unidirectional anisotropy byheat-treating in the magnetic field, the directions of themagnetizations of the magnetic layers FM and C2 which are adjacent tothe antiferromagnetic layers AF1 and AF2 turn into the same directions.Since the magnetically fixed layer C1 is carrying out theantiferromagnetic coupling with the magnetic layer FM, the magnetizationM1 can be fixed to have the reverse direction to the magnetization M3 ofthe magnetic layer FM.

In addition, in the case of this structure, it is desirable to pass thewriting current I in the recording layer A between the magneticallyfixed layers C1 and C2, as expressed with the arrow I1 in this figure(or the reverse direction to this arrow). However, from the viewpoint ofactual use, it is easier to pass the current between theantiferromagnetic layers AF1 and AF2 using the electrodes provided onthe antiferromagnetic layer AF1 and under the antiferromagnetic layerAF2 which is not shown as expressed with the arrow I2 in this figure (orthe reverse direction to this arrow) The recording layer A can also bewritten-in with such a current.

FIG. 16 also shows a schematic section view showing the other example ofthe magnetic cell where the magnetizations of the magnetically fixedlayers C1 and C2 are fixed by the antiferromagnetic layers,respectively.

That is, in this example, the magnetic layers FM1 and FM2 and theantiferromagnetic layers AF1 and AF2 are provided outside themagnetically fixed layers C1 and C2 through the non-magnetic layers ACand FC.

The non-magnetic layer AC has the thickness with which theantiferromagnetic exchange coupling between the magnetic layers of theboth sides. On the other hand, the non-magnetic layer FC has thethickness with which the coupling between the magnetic layers of theboth sides becomes ferromagnetically.

Generally, the interlayer exchange coupling between two ferromagneticlayers through the non-magnetic layer oscillates between positive(ferromagnetic coupling) and negative (antiferromagnetic coupling)depending on the thickness of the non-magnetic layer, as expressed inFIG. 17. Therefore, it is desirable to set the thicknesses of thenon-magnetic layers AC and FC so that two peaks may be corresponded tothe different symbols in FIG. 16. For example, t1 should be made intothe thickness of the non-magnetic layer AC, and t2 should be made intothe thickness of the non-magnetic layer FC, in FIG. 17.

In such a structure, the magnetizations of the magnetic layers FM1 andFM2 which are adjacent to the antiferromagnetic layers AF1 and AF2 canbe made to have the same directions by giving the unidirectionalanisotropy by the antiferromagnetic layers AF1 and AF2, and finally themagnetizations of the magnetically fixed layers C1 and C2 can be fixedto be anti-parallel.

Or, the magnetizations of the magnetically fixed layers C1 and C2 may befixed by the hard magnet provided adjacent to these layers. Or, the hardmagnet may be used for the magnetically fixed layer C1 or C2. Magneticmaterials, such as cobalt platinum (CoPt), iron platinum (FePt), andcobalt chromium platinum (CoCrPt), can be used as the hard magnet inthis case.

In addition, in the case of this structure, it is desirable to pass thewriting current I in the recording layer A between the magneticallyfixed layers C1 and C2, as expressed with the arrow I1 in this figure(or the reverse direction to this arrow). However, from the viewpoint ofactual use, it is easier to pass the current between theantiferromagnetic layers AF1 and AF2 using the electrodes provided onthe antiferromagnetic layer AF1 and under the antiferromagnetic layerAF2 which is not shown as expressed with the arrow I2 in this figure (orthe reverse direction to this arrow) The recording layer A can also bewritten-in with such a current.

In the above, the method of making the magnetizations M1 and M2 of themagnetically fixed layers C1 and C2 being anti-parallel in the magneticcell of the invention was explained.

Now, the invention can be adapted in not only the case that one magneticrecording layer A is provided but also the case that a plurality ofmagnetic recording layers A is provided.

FIG. 18 shows a schematic section view showing the magnetic cellprovided the two magnetic recording layers. That is, in this magneticcell, the magnetically fixed layer C1, the intermediate layer B1, themagnetic recording layer A1, intermediate layer B2, the magneticallyfixed layer C2, the intermediate layer B3, the magnetic recording layerA2, the intermediate layer B4, and the magnetically fixed layer C3 arelaminated in this order. Namely, this magnetic cell has the structurewhere the magnetic cells illustrated in FIG. 1 are formed in series atthe top and bottom of the magnetically fixed layer C2 sharing themagnetically fixed layer C2. Thus, a reproduction output signal can beincreased by laminating the two recording layers A1 and A2 in series.

And, in FIG. 18, if the magnetization reversal currents of the magneticrecording layers A1 and A2 are differentiated by differentiating thethicknesses and/or materials of the magnetic recording layers A1 and A2,multi-valued recording will be attained. Moreover, the multi-valuedrecord with more kinds of data can also be attained by laminating thethree or more magnetic recording layers in series. In addition, themagnetization of the magnetically fixed layer C2 can be fixed moreeffectively by inserting the antiferromagnetic layer in the C2 layer andgiving the unidirectional anisotropy.

In the invention, the magnetically fixed layer C1 (and/or C2) can bemade into a plurality of layers, or the magnetic recording layer A canbe made into a plurality of layers. Especially, when a laminated filmwith an antiferromagnetic coupling of ferromagnetic layer/non-magneticlayer/ferromagnetic layer is used as the magnetically fixed layer C1 (orC2), the magnetization reversal of the magnetic recording layer A can beattained with smaller current. The structure mentioned above about FIG.15 can be mentioned as this example.

That is, in this figure, the laminated structure which consists of themagnetic layer FM, the non-magnetic layer AC, and the magnetically fixedlayer C1 can be regarded as “the magnetically fixed structure P1.” Whenthe magnetization direction of the magnetically fixed layer C1 beingadjacent to the intermediate layer B1 of the magnetically fixedstructure P1 is anti-parallel to the magnetization direction of themagnetically fixed layer C2, the effect of the invention is acquired, asexpressed in FIG. 14. In this structure, the magnetization directions ofthe outmost ferromagnetic layers (the magnetic layer FM of themagnetically fixed structure P1 and the magnetically fixed layer C2) isparallel. This results in a merit that a formation process becomes easy,since the same material is used for the antiferromagnetic by which theunidirectional anisotropies are introduced to the two outmostferromagnetic layers, and onetime annealing process can generate theunidirectional anisotropies into the both two outmost ferromagneticlayers.

FIG. 19 shows a schematic section view showing an example where themagnetically fixed layer and the magnetic recording layer A arelaminated structures, respectively.

That is, the laminated structure which consists of the magnetic layerFM/the non-magnetic layer AC/the magnetically fixed layer C1 whosemagnetizations are coupled antiferromagnetically is provided as themagnetically fixed structure P1. Furthermore, the laminated structurewhich consists of the magnetic layer A1/the non-magnetic layer AC/themagnetic layer A2/the non-magnetic layer AC/the magnetic layer A3 withantiferromagnetic coupling between two adjacent magnetic layers acrossnon-magnetic layer is provided as the magnetic recording layer A.

In this structure, when the magnetization direction of the magneticallyfixed layer C1 which is adjacent to the intermediate layer B1 isanti-parallel to the magnetization direction of the magnetically fixedlayer C2, and the magnetization directions of the magnetic layers A1 andA2 which are adjacent to the intermediate layers B1 and B2 respectivelyof the magnetic recording layers A are parallel, the effect of theinvention is acquired.

The effective saturated magnetization per unit volume of the magneticrecording layer can be reduced by making the magnetic recording layer Ato be the laminated structure with antiferromagnetic coupling. That is,since the magnetic energy of the magnetic recording layer A can bereduced, the critical current required for the magnetization reversal,i.e., for writing-in, can be lowered.

And, in this structure, the magnetization directions of two outermostmagnetic layers (the magnetic layer FM and magnetically fixed layer C2of the magnetically fixed structure P1) are parallel by providing themagnetically fixed structure P1. This results in a merit that aformation process becomes easy, since the same material is used for theantiferromagnetic layers which are not illustrated, by which theunidirectional anisotropies are introduced to the two outmostferromagnetic layers, and onetime annealing process can generate theunidirectional anisotropies into the both two outmost ferromagneticlayers.

FIG. 20 is also a schematic section view showing an example where themagnetically fixed layer and the magnetic recording layer A arelaminated structures, respectively. That is, the laminated structurewhich consists of the magnetic layer FM/non-magnetic layer AC/themagnetically fixed layer C1 whose magnetizations combine anti-parallelis provided as the magnetically fixed structure P1. And, the laminatedstructure which consists of the magnetic layer A1/the non-magnetic layerFC/the magnetic layer A2 with ferromagnetic coupling is provided as themagnetic recording layer A.

In this structure, when the magnetization direction of the magneticallyfixed layer C1 which is adjacent to the intermediate layer B1 isanti-parallel to the magnetization direction of the magnetically fixedlayer C2, and the magnetization directions of the magnetic layers A1 andA2 which are adjacent to the intermediate layers B1 and B2 respectivelyof the magnetic recording layers A are parallel, the effect of theinvention is acquired.

The effective saturated magnetization per unit volume of the magneticrecording layer can be reduced by making the magnetic recording layer Ato be the laminated structure with ferromagnetic coupling. That is,since the magnetic energy of the magnetic recording layer A can bereduced, the critical current required for the magnetization reversal,i.e., for writing-in, can be lowered.

And, in this structure, the magnetization directions of two outermostmagnetic layers (the magnetic layer FM and magnetically fixed layer C2of the magnetically fixed structure P1) are parallel by providing themagnetically fixed structure P1. This results in a merit that aformation process becomes easy, since the same material is used for theantiferromagnetic layers which are not illustrated, by which theunidirectional anisotropies are introduced to the two outmostferromagnetic layers, and onetime annealing process can generate theunidirectional anisotropies into the both two outmost ferromagneticlayers.

FIG. 21 also shows a schematic section view showing an example where themagnetically fixed layer and the magnetic recording layer A arelaminated structures, respectively. That is, the laminated structurewhich consists of the magnetic layer FM/non-magnetic layer AC/themagnetically fixed layer C1 whose magnetizations couple anti-parallel isprovided as the magnetically fixed structure P1. And, the laminatedstructure which consists of the magnetic layer A1/the magnetic layerA2/the magnetic layer A3 is provided as the magnetic recording layer A.

In this structure, when the magnetization direction of the magneticallyfixed layer C1 which is adjacent to the intermediate layer B1 isanti-parallel to the magnetization direction of the magnetically fixedlayer C2 which is adjacent to the intermediate layer B2 and themagnetization directions of the magnetic layers A1, A2 and A3 of themagnetic recording layers A are parallel, the effect of the invention isacquired.

In the magnetic recording layer A which has the laminated structure withferromagnetic coupling, the magnetization reversal current can bereduced because a permalloy with small saturation magnetization etc. canbe used for the central magnetic layer (A2), and material with largespin asymmetry, such as CoFe, can be used for outside magnetic layers(A1, A3). That is, the effect that the critical current of writing-incan be lowered is acquired.

And, in this structure, the magnetization directions of two outermostmagnetic layers (the magnetic layer FM and magnetically fixed layer C2of the magnetically fixed structure P1) are parallel by providing themagnetically fixed structure P1. This results in a merit that aformation process becomes easy, since the same material is used for theantiferromagnetic layers which are not illustrated, by which theunidirectional anisotropies are introduced to the two outmostferromagnetic layers, and onetime annealing process can generate theunidirectional anisotropies into the both two outmost ferromagneticlayers.

FIG. 22 shows a schematic section view showing the example in which twomagnetically fixed structures are provided. That is, the laminatedstructure which consists of the magnetic layer FM/non-magnetic layerAC/the magnetically fixed layer C1 whose magnetizations coupleanti-parallel is provided as the magnetically fixed structure P1. And,the laminated structure which consists of the magnetically fixed layerC2/the non-magnetic layer AC/the magnetic layer FM/the non-magneticlayer AC/the magnetic layer FM whose magnetizations couple anti-parallelis provided as the magnetic recording layer A.

In this structure, when the magnetization direction of the magneticallyfixed layer C1 which is adjacent to the intermediate layer B1 of themagnetically fixed structure P1 is anti-parallel to the magnetizationdirection of the magnetically fixed layer C2 which is adjacent to theintermediate layer B2 of the magnetically fixed structure P2, the effectof the invention is acquired. And, in this structure, the total numberof the magnetic layers which constitute the magnetically fixed structureP1 is even, and the total number of the magnetic layers which constituteP2 is odd.

Thus, the magnetization directions of two outermost magnetic layers (themagnetic layer FM of the top of the magnetically fixed structure P1 andthe magnetic layer FM of the bottom of the magnetically fixed structureP2) are fixed to be parallel. This results in a merit that a formationprocess becomes easy, since the same material is used for theantiferromagnetic layers which are not illustrated, by which theunidirectional anisotropies are introduced to the two outmostferromagnetic layers, and onetime annealing process can generate theunidirectional anisotropies into the both two outmost ferromagneticlayers.

FIG. 23 shows a schematic section view showing an example where themagnetic recording layer is also the laminated structure in addition tothe two magnetically fixed structures. That is, the laminated structurewhich consists of the magnetic layer FM/non-magnetic layer AC/themagnetically fixed layer C1 whose magnetizations couple anti-parallel isprovided as the magnetically fixed structure P1. And, the laminatedstructure which consists of the magnetically fixed layer C2/thenon-magnetic layer AC/the magnetic layer FM/the non-magnetic layerAC/the magnetic layer FM whose magnetizations couple anti-parallel isprovided as the magnetically fixed structure P2. And, the laminatedstructure which consists of the magnetic layer A1/the non-magnetic layerAC/the magnetic layer A2/the non-magnetic layer AC/the magnetic layer A3which carry out antiferromagnetic couplings is provided as the magneticrecording layer A.

In this structure, when the magnetization direction of the magneticallyfixed layer C1 which is adjacent to the intermediate layer B1 of themagnetically fixed structure P1 is anti-parallel to the magnetizationdirection of the magnetically fixed layer C2 which is adjacent to theintermediate layer B2 of the magnetically fixed structure P2, and themagnetization directions of the magnetic layers A1 and A3 which areadjacent to the intermediate layers B1 and B2 respectively of themagnetic recording layers A are parallel, the effect of the invention isacquired. And, in this structure, the total number of the magneticlayers which constitute the magnetically fixed structure P1 is even, andthe total number of the magnetic layers which constitute P2 is odd.Thus, the magnetization directions of two outermost magnetic layers (themagnetic layer FM of the top of the magnetically fixed structure P1 andthe magnetic layer FM of the bottom of the magnetically fixed structureP2) are fixed to be parallel. This results in a merit that a formationprocess becomes easy, since the same material is used for theantiferromagnetic layers which are not illustrated, by which theunidirectional anisotropies are introduced to the two outmostferromagnetic layers, and onetime annealing process can generate theunidirectional anisotropies into the both two outmost ferromagneticlayers.

FIG. 24 also shows a schematic section view showing an example where themagnetic recording layer is the laminated structure in addition to thetwo magnetically fixed structures. That is, the laminated structurewhich consists of the magnetic layer FM/non-magnetic layer AC/themagnetically fixed layer C1 whose magnetizations couple anti-parallel isprovided as the magnetically fixed structure P1. And, the laminatedstructure which consists of the magnetically fixed layer C2/thenon-magnetic layer AC/the magnetic layer FM the non-magnetic layerAC/the magnetic layer FM whose magnetizations couple anti-parallel isprovided as the magnetically fixed structure P2. And, the laminatedstructure which consists of the magnetic layer A1/the non-magnetic layerFC/the magnetic layer A2 which carry out antiferromagnetic couplings isprovided as the magnetic recording layer A.

In this structure, when the magnetization direction of the magneticallyfixed layer C1 which is adjacent to the intermediate layer B1 of themagnetically fixed structure P1 is anti-parallel to the magnetizationdirection of the magnetically fixed layer C2 which is adjacent to theintermediate layer B2 of the magnetically fixed structure P2 and themagnetization directions of the magnetic layers A1 and A2 of themagnetic recording layers A are parallel, the effect of the invention isacquired. And, also in this structure, the total number of the magneticlayers which constitute the magnetically fixed structure P1 is even, andthe total number of the magnetic layers which constitute P2 is odd.Thus, the magnetization directions of two outermost magnetic layers (themagnetic layer FM of the top of the magnetically fixed structure P1 andthe magnetic layer FM of the bottom of the magnetically fixed structureP2) are fixed to be parallel. This results in a merit that a formationprocess becomes easy, since the same material is used for theantiferromagnetic layers which are not illustrated, by which theunidirectional anisotropies are introduced to the two outmostferromagnetic layers, and onetime annealing process can generate theunidirectional anisotropies into the both two outmost ferromagneticlayers.

FIG. 25 also shows a schematic section view showing an example where themagnetic recording layer is the laminated structure in addition to thetwo magnetically fixed structures. That is, the laminated structurewhich consists of the magnetic layer FM/non-magnetic layer AC/themagnetically fixed layer C1 whose magnetizations combine anti-parallelis provided as the magnetically fixed structure P1. And, the laminatedstructure which consists of the magnetically fixed layer C2/thenon-magnetic layer AC/the magnetic layer FM/the non-magnetic layerAC/the magnetic layer FM whose magnetizations combine anti-parallel isprovided as the magnetically fixed structure P2. And, the laminatedstructure which consists of the magnetic layer A1/the magnetic layerA2/the magnetic layer A3 is provided as the magnetic recording layer A.

In this structure, when the magnetization direction of the magneticallyfixed layer C1 which is adjacent to the intermediate layer B1 of themagnetically fixed structure P1 is anti-parallel to the magnetizationdirection of the magnetically fixed layer C2 which is adjacent to theintermediate layer B2 of the magnetically fixed structure P2 and themagnetization directions of the magnetic layers A1, A2 and A3 of themagnetic recording layers A are parallel, the effect of the invention isacquired.

And, also in this structure, the total number of the magnetic layerswhich constitute the magnetically fixed structure P1 is even, and thetotal number of the magnetic layers which constitute P2 is odd. Thus,the magnetization directions of two outermost magnetic layers (themagnetic layer FM of the top of the magnetically fixed structure P1 andthe magnetic layer FM of the bottom of the magnetically fixed structureP2) are fixed to be parallel. This results in a merit that a formationprocess becomes easy, since the same material is used for theantiferromagnetic layers which are not illustrated, by which theunidirectional anisotropies are introduced to the two outmostferromagnetic layers, and onetime annealing process can generate theunidirectional anisotropies into the both two outmost ferromagneticlayers.

In the invention shown in FIG. 15 and FIGS. 19-25, it is possible toreverse the magnetization of the magnetic recording layer with currentsmaller than that for the cell with a single layer of the same thicknessby adopting the laminated structures with antiferromagnetic coupling asmagnetically fixed structures P1 and P2 as explained referring toexamples.

Furthermore, it is also possible to reduce the leak magnetic fieldgenerated from the edge of the magnetic layer and avoid the problems,such as a cross talk, by using the laminated structure withantiferromagnetic coupling.

Especially, as for the magnetically fixed layer which is far apart formthe substrate, it is easy to generate the leak magnetic field since thesize of the in-plane direction of this layer is inevitable to be smallbecause of a micro fabrication. The magnetic bias due to this leakmagnetic field makes the reversal current larger than the case wherethere is no magnetic field bias in any direction, by shifting thereversal current.

In contrast, by adopting the magnetically fixed structure by thelaminated film with antiferromagnetic coupling, the shift of thereversal current is prevented and the reversal current can be kept beinglow in either reversal direction.

As explained above, in the invention, it becomes possible to control themagnetization of the magnetic recording layer with small current, andalso to read-out the magnetic cell. Therefore, magnetic memories, suchas probe storage and a solid-state memory with small power consumptionand high reliability can be produced by arranging a plurality ofmagnetic cells of the invention, as explained later in detail.

Next, each element which constitutes the magnetic cell of the inventionwill be explained in full detail.

As a material of the magnetically fixed layers C1 and C2 and themagnetic recording layer A, iron (Fe), cobalt (Co), nickel (Ni), thealloy including at least one element selected from the group consistingof iron (Fe), cobalt (Co), nickel (Ni), manganese (Mn), and chromium(Cr) or the group consisting of iron (Fe), cobalt (Co), nickel (Ni),manganese (Mn), and chromium (Cr), a NiFe system alloy called a“permalloy”, a CoNbZr system alloy, a FeTaC system alloy, a CoTaZrsystem alloy, a FeAlSi system alloy, a FeB system alloy, a softmagnetism material such as a CoFeB system alloy, the Heusler alloy, amagnetic semiconductor, or half metal magnetic material oxides or halfmetal magnetic material nitride such as CrO₂, Fe₃O₄, andLa_(1-x)Sr_(x)MnO₃ can be used.

As the “magnetic semiconductor”, a magnetic element at least one of iron(Fe), cobalt (Co), nickel (Ni), chromium (Cr), and manganese (Mn), andelements consisting of compound semiconductors or oxide semiconductorscan be used. Specifically, (Ga, Cr)N, (Ga, Mn)N, MnAs, CrAs, (Ga, Cr)As,ZnO:Fe, (Mg, Fe)O, etc. can be mentioned, for example.

In the invention, the material with the magnetic characteristic whichsuits the use can be chosen appropriately in these materials and used asmaterials of magnetically fixed layers C1 and C2 and the magneticrecording layer A. However, it is desirable to combine materials of eachlayer so that both of the magnetoresistance effect through theintermediate layer B1 and the magnetoresistance effect through theintermediate layer B2 may be of the normal type or of the reverse type.The combinations will be explained later.

And, continuous magnetic materials, or complex structures formed byparticulates which are consisted of magnetic materials in non-magneticmatrix being deposited or formed, can be used as materials for thesemagnetism layers. As such a complex structure, the so-called “granularmagnetic material” can be mentioned, for example.

When at least one of the magnetically fixed layers C1 and C2 forms amultilayer, such as the magnetic layer/the non-magnetic layer/themagnetic layer, the magnetic layer/the non-magnetic layer/the magneticlayer/the non-magnetic layer/the magnetic layer, or the magneticlayer/the magnetic layer, it is desirable to make the magnetizationdirection of the magnetically fixed layer C1 (or C2) which is adjacentdirectly to the intermediate layer B1 (or B2) to be anti-parallel to themagnetization direction of the magnetically fixed layer C2 (or C1) whichis adjacent to the intermediate layer B2.

The Inventors found out that the magnetization reversal of the magneticrecording layer A can be carried out with smaller current when themagnetically fixed layer C1 (or C2) is the laminated structure of theferromagnetic layer/the non-magnetic layer/the ferromagnetic layer withantiferromagnetic coupling between two adjacent ferromagnetic layers. Itis thought that this is based on the spin dependent scattering andreflection effects of the non-magnetic layer which arisesantiferromagnetic coupling. Moreover, the shift of the characteristic tothe magnetic field can be prevented by using such a laminated film ofthree layers for the magnetically fixed layer C1 (or C2).

In the structure expressed in FIG. 15 etc., the ferromagnetic layer FMthrough the non-magnetic layer AC are magnetically fixed in addition tothe magnetically fixed layer C2. Then, in the example mentioned later,these three layers may be collectively called the “magnetically fixedlayer.”

Furthermore, as a material of the magnetic recording layer A, thelaminated structure of double layer consisting of [(Co or CoFealloy)/(the permalloy alloy or nickel which consists of NiFe orNiFeCo)], or the triple layer consisting of [(Co or CoFealloy)/(permalloy alloy or nickel which consists of NiFe or NiFeCo)/(Coor CoFe alloy)] can be used. It is desirable for the thickness of Co orCoFe of outside to be in a range between 0.2 nm and 1 nm in the magneticlayer which has multilayer structure.

According to this structure, the magnetization reversal can be obtainedwith smaller current. Moreover, the magnetic recording layer A may be amultilayer where the magnetic layers are laminated. In this case, all ofthe magnetization of each magnetic layer which constitutes thismultilayer may be in the same direction, or the magnetizations of twomagnetic layers of the outside which contact the two intermediate layersB1 and B2 of the plurality of magnetic layers which constitute themagnetic recording layer A directly may be parallel. It is difficult toacquire the effect of the invention when the magnetizations of twomagnetic layers of the outside which touch the two intermediate layersB1 and B2 are anti-parallel.

In either case, it is also advantageous for the writing-in of themagnetization to the magnetic recording layer A to make themagnetization easy axis of the magnetic recording layer A in parallel(or in anti-parallel) to the magnetization axes of the magnetization M1and M2 of the magnetically fixed layers C1 and C2.

On the other hand, as a material of the intermediate layers B1 and B2,copper (Cu), gold (Au), silver (Ag), ruthenium (Ru), an alloy includingat least one element selected from the group consisting of copper (Cu),gold (Au), silver (Ag), and ruthenium (Ru), an insulator consisting of aoxide, a nitride, or a fluoride including at least one element selectedfrom the group consisting of Aluminum (Al), titanium (Ti), tantalum(Ta), cobalt (Co), nickel (Ni), silicon (Si), and iron (Fe) can be used.Elements of different kinds, such as oxygen, may be added in theelectric conduction layer. And, the elements of different kinds may formthe discontinuous high resistance thin film.

Furthermore, pinholes may be formed in an insulating layer and themagnetic layer may reach them. Moreover, it is desirable to use thematerials with which both of the magnetoresistance effects become of thenormal type or both of the magnetoresistance effects become of thereverse type, as the materials of the intermediate layer B1 and B2.

The combination of the material of the intermediate layer and thematerials of the magnetic layers of the both sides decides whether themagnetoresistance effect becomes of the normal type or of the reversetype.

In the invention, it is not desirable to use the combinations ofmaterials with which one is of the normal type and the other is of thereverse type. Here, as mentioned above, the “normal type” correspondsthe case where the resistance becomes large when the magnetizationdirections of magnetic layers provided on both sides of the intermediatelayer are anti-parallel. And, the “reverse type” corresponds the casewhere the resistance becomes small when the magnetization directions ofmagnetic layers provided on both sides of the intermediate layer areanti-parallel. The reason why it is not desirable to use thecombinations of normal type and reverse type is as the following:

That is, in the reverse type, the reverse spin to the spin of the normaltype contributes to the conduction (tunneling is also included).Therefore, the resistance becomes small when the magnetizationdirections of magnetic layers provided on both sides of the intermediatelayer are anti-parallel. However, since the electron with reverse spincontributes to the conduction (tunneling is also included), the write-indirection becomes reverse direction to the normal type.

Therefore, when passing current towards the magnetic recording layer Afrom the magnetically fixed layer C1 (or C2), the magnetization of themagnetic recording layer A is anti-parallel to the magnetization of themagnetically fixed layer C1 (or C2). And, when passing current towardsthe magnetically fixed layer C1 (or C2) from the magnetic recordinglayer A, the magnetization of the magnetic recording layer A is parallelto the magnetization of the magnetically fixed layer C1 (or C2).

Therefore, the effect of the invention can not be acquired when one ofthe intermediate layers B1 and B2 is of the normal type and the other isof the reverse type, combining with the materials of the magnetic layersof the both sides. That is, in this invention, it is necessary to makethe magnetization directions of the outer magnetically fixed layers C1and C2 anti-parallel, and to combine the materials of the magneticlayers with the intermediate layers appropriately so that both of themagnetoresistance effect through the intermediate layer B1 and themagnetoresistance effect through the intermediate layer B2 may be of thenormal type or both may be of the reverse type.

As the materials of the intermediate layer B1 and B2 for obtaining thenormal type magnetoresistance effect, copper (Cu), silver (Ag), gold(Au), and these compounds, insulator with hole filled with alumina,magnesium oxide (MgO), nitride aluminum (Al—N), oxidization nitridesilicon (Si—O—N), or copper (Cu), and insulator with hole filled withmagnetic materials can be mentioned.

In addition to the above materials as the materials of the intermediatelayer B1 and B2, as the materials of the magnetically fixed layers C1and C2, Co, Fe, Ni, CoFe, alloy containing Mn or Cr, and so-called metalsystem ferromagnetic material such as CoFeB or Heusler alloy can bementioned. Then, the normal type magnetoresistance effect is obtainedbetween the magnetically fixed layer C1 and the magnetic recording layerA and between the magnetically fixed layer C2 and the magnetic recordinglayer A.

Moreover, when using the magnetic material of the oxide system such asCrO₂, Fe₃O₄, and La_(1-x)Sr_(x)MnO₃ for the magnetic layers, the normaltype magnetoresistance effect is obtained only when the materials of themagnetically fixed layers C1 and C2 and the material of the magneticrecording layer A are the same.

As the materials of the intermediate layers B1 and B2 for obtaining thereverse type magnetoresistance effect, oxidization tantalum (Ta—O) etc.can be mentioned. When the so-called metal system ferromagneticmaterials mentioned above are used as materials of the magneticallyfixed layers C1 and C2 and the magnetic recording layer A, the reversetype magnetoresistance effect is obtained by combining with theintermediate layers B1 and B2 of the oxidization tantalum.

Furthermore, as the combination of the magnetic layer/the intermediatelayer/the magnetic layer from which the reverse type magnetoresistanceeffect is obtained, the combination of the metallic magnetic layer/theoxide insulator intermediate layer/the oxide magnetic layer can bementioned.

For example, Co/SrTiO₃/La_(0.7)Sr_(0.3)MnO₃, andCo₉Fe/SrTiO₃/La_(0.7)Sr_(0.3)MnO₃ etc can be used. Moreover, thecombination of the magnetite/the insulator intermediate layer/theperovskite system oxide magnetic material ofFe₃O₄/CoCr₂O₄/La_(0.7)Sr_(0.3)MnO₃.etc can be mentioned as thecombination of the magnetic layer/the intermediate layer/the magneticlayer from which the reverse type magnetoresistance effect is obtained.Furthermore, the combination of CrO₂/Cr oxide insulator/Co can bementioned as a combination of the magnetic the layer/the intermediatelayer/the magnetic layer from which the reverse type magnetoresistanceeffect is obtained.

On the other hand, it is desirable to use iron manganese (FeMn),platinum manganese (PtMn), palladium manganese (PdMn), palladiumplatinum manganese (PdPtMn), iridium manganese (IrMn), platinum iridiummanganese (PtIrMn), etc. as a material of the antiferromagnetic layer AFfor fixing the magnetizations of the magnetically fixed layers C1 andC2. Moreover, it is desirable to use the material including at least oneof copper (Cu), gold (Au), silver (Ag) and ruthenium (Ru), or the alloycontaining these materials as the non-magnetic layer for fixing themagnetizations by exchange coupling between ferromagnetic layers.

It is desirable to make the thicknesses of the magnetically fixed layersC1 and C2 in a range between 0.6 nm and 100 nm, and to make thethickness of the magnetic recording layer A in a range between 0.2 nmand 50 nm. Moreover, it is desirable to make the thicknesses of theintermediate layers B1 and B2 of the conductor in a range between 0.2 nmand 20 nm, and to make the thicknesses of the intermediate layers B1 andB2 containing insulator in a range between 0.2 nm and 50 nm.

On the other hand, as for the plane shape of the magnetic element, forexample, it is desirable to make the plane shape of the record magneticlayer C to form into a shape of a rectangular, an elongated hexagonal,an ellipse, a rhomboid or a parallelogram. As for the aspect ratio, itis desirable to set it in a range about from 1:1 to 1:5 so that auniaxial magnetic anisotropy can be introduced without forming the edgedomains.

However, in the case of the cell in a doughnut shape, it is desirable toshape the form where a magnetic vortex domain is easy to be formedexceptionally.

It is desirable to make the length of one side of the longitudinaldirection of the magnetic recording layer A in a range between 5 nm and1000 nm.

In addition, although the examples where the sizes of the directions ofa film plane in the magnetically fixed layers C1 and C2 and that in themagnetic recording layer A are the same are expressed in FIG. 1, etc,the invention is not limited to these examples. That is, the magneticcell may be formed having different size of each layer, for connectingwirings or for controlling the magnetization direction. Moreover, theshape of each layer of the magnetic cell may be different from eachother.

As explained above, in the magnetic cell of the invention, themagnetization can be written in the magnetic recording layer A withsmall write-in current by the spin-polarized current. Furthermore, themagnetization of the magnetic recording layer A can also be read out bythe magnetoresistance effect. And the magnetic cell of the invention hasthe advantage that the formation of an array or the integration is easy,for its small size.

Since the magnetic cell of the invention is minute and has a write-infunction and a read-out function, it can be applied to various kinds ofuses. Next, the example where the magnetic cells of the invention arearranged and used for a recording-reproducing equipment will beexplained.

FIG. 26 is a schematic diagram showing the magnetic memory using themagnetic cell of this example. That is, this example is a probe storagewhich applies the magnetic cell of the invention to the so-called“patterned media” and accesses it with the probe.

The recording medium has the structure where the magnetic cells 10 ofthe invention are arranged in the plane of the insulators 100 with highresistance in a matrix fashion, on the conductive substrate 110. In themagnetic memory, a probe 200 is formed on the surface of a medium forselecting these magnetic cells, and a drive mechanism 210 forcontrolling the relative location between the probe 200 and the surfaceof the medium, a power supply 220 for applying current or voltage to themagnetic cells 10 from the probe 200 and a detector circuit 230 fordetecting the internal magnetization state of the magnetic cells aschanges of resistances are provided.

In the example expressed in FIG. 26, although the drive mechanism 210 isconnected to the probe 200, since the relative position of the probe tothe medium should just change, the drive mechanism 210 may be providedin the medium side. As expressed in this figure, a plurality of magneticcells 10 of the invention is made to arrange on the conductive substrate110, and it is considered as the patterned medium. And writing andrecording are performed by passing the current through the magneticcells 10 between the conductive probe 200 and the substrate 110.Moreover, although the cells 10 share only the bottom electrode in thesubstrate 110 in the example expressed in FIG. 26, the cells 10 mayshare the layers of their cells as expressed in FIG. 27. In suchstructure, the manufacturing process becomes simpler and thecharacteristics can be uniformed further.

The selection of one of the magnetic cell from the magnetic cells 10 isperformed by changing the relative location between the conductive probe200 and the patterned medium. It is necessary for the conductive probe200 only to be connected to a magnetic cell 10 electrically. Theconductive probe 200 may touch the magnetic cell 10, or does not need totouch the magnetic cell 10. When the conductive probe 200 does not touchthe magnetic cell 10, recording and reproduction can be performed usingthe tunnel current flowing between the magnetic cell 10 and the probe200 or the current by the field emission.

The recording in the magnetic cell 10 is performed by the currentflowing to the magnetic cell 10 from the probe 200 which accessed themagnetic cell, or the current flowing from the magnetic cell 10 to theprobe 200. When the magnetization reversal current determined with thesize, structure, composition, etc. of the magnetic cells 10 is Is, therecording can be performed by passing the write-in current Iw largerthan Is to the cells. The direction of the magnetization recorded is thesame as the direction of the magnetization of the magnetically fixedlayer through which the electron current passes first, in the case wherethe magnetic cell consists of the normal type and normal typecombination. Therefore, the writing of “0” or “1” can be appropriatelyperformed by reversing the electronic flow, i.e., the polarity of thecurrent.

The reproduction is performed by the current flowing from the probe 200accessing to the magnetic cells 10, or the current flowing to the probe200, as well as the record. However, when reproducing, the reproductioncurrent Ir smaller than the magnetization reversal current Is is passed.And the record state of the magnetic recording layer A is judged bydetecting the voltage or the resistance (when the voltage is applied, bydetecting the current). Therefore, in the magnetic memory of thisexample, the recording is attained by passing larger current Iw than Ir.

FIG. 28 is a schematic section view showing the second example of themagnetic memory using the magnetic cells of the invention.

That is, the magnetic memory of this example has the structure where theparallel arrangement of a plurality of the magnetic cells 10 is arrangedon the electrode layer (lower wiring) 110. The magnetic cells 10 areelectrically isolated with the insulators 100. The wirings 120 which areso-called the bit line and the word line are connected to each magneticcell 10. The specific magnetic cell 10 can be selected by specifying thebit line and the word line.

The record to the magnetic cells 10 is performed by the current passingfrom the wirings 120 to the magnetic cells 10, or the current passingfrom the magnetic cells 10 to the wirings 120. It becomes possible torecord by passing through the cells the write-in current Iw larger thanthe magnetization reversal current Is which is determined with the size,structure, composition, etc. of the magnetic cells 10. The direction ofthe magnetization recorded is the same as the direction of themagnetization of the magnetically fixed layer through which the electroncurrent passes first, in the case where the magnetic cell consists ofthe normal type and normal type combination. Therefore, the writing of“0” and “1” can be performed by reversing the electronic flow, i.e., thepolarity of the current.

The reproduction is performed by the current passing from the wiringswhich accessed to the magnetic cells 10 or the current passing to thewirings, as well as the record. But, when reproducing, the reproductioncurrent Ir smaller than Is is passed. And the record state is judged bydetecting the voltage or the resistance (when the voltage is applied, bydetecting the current). Therefore, also in the magnetic memory of thisexample, the recording is attained by passing the larger current Iw thanIr.

Examples

Hereafter, the embodiment of the invention will be explained in moredetail, referring to examples.

First Example

FIG. 29A is a schematic diagram showing the principal cross-sectionalstructure of the magnetic cell of this example, and FIG. 29B is aschematic diagram showing the principal cross-sectional structure of themagnetic cell of the comparative example.

That is, the magnetic cell of this example (sample I) has the structurewhere the electrode EL 1, the magnetically fixed layer C1, theintermediate layer B1, the magnetic recording layer A,intermediate-layer B2, the magnetically fixed layer C2, and theelectrode EL 2 are laminated. Moreover, the magnetic cell of thecomparative example (sample II) has the structure where the electrode EL1, the magnetic recording layer A, the intermediate layer B, themagnetically fixed layer C, and the electrode EL2 are laminated. Thematerial and the thickness of each layer are as the following:

-   -   Sample I: EL1(Cu)/C1(Co: 20 nm)/B1(Cu: 10 nm)/A(Co: 3 nm)/B2(Cu:        6 nm)/C2(Co: 20 nm)/EL2 (Cu)    -   Sample II: EL1(Cu)/A(Co: 3 nm)/B(Cu: 6 nm)/C (Co: 20 nm)/EL2        (Cu)

The laminated structure is formed on the lower electrode EL2 byultrahigh-vacuum sputtering equipment. And the resist was applied afterforming the tantalum (Ta) protective film which is not illustrated onthe cell. Then, EB (electron beam) dwaring was carried out, the mask wasformed, and the cell was processed by the ion milling. The processingsize of the cell was 100 nm×50 nm.

The value of the magnetization reversal current of the magneticrecording layer A was obtained from the change of the resistance to theamount of the current perpendicularly passed to the film plane about theobtained sample. As a result, the average value of the positive/negativereversal current was 3.1 mA at Sample I and 1.4 mA at Sample II. And,although the asymmetry over positive/negative current was seen at SampleII, this asymmetry was canceled at Sample I.

That is, by providing the two magnetically fixed layers C1 and C2 whosemagnetizations were anti-parallel, the magnetization reversal current ofthe recording layer A decrease and the improvement of the symmetry ofthe write-in current was found. It is thought that the symmetry of thewrite-in current was improved because the magnetic cell became moresymmetrical against the polarity of the current by providing themagnetically fixed layers C1 and C2 of the antiferromagnetic arrangementwith the anti-parallel magnetization directions.

Second Example

Next, the example of the magnetic cell of the structure expressed inFIG. 15 will be explained as the second example of the invention. Inaddition, in this example, the magnetic cell of the laminated structurewhich was reversed the upper and lower sides to FIG. 15 was made as anexperiment.

First, the lower electrode EL 1 which consists of tantalum (Ta) andcopper (Cu) was formed on the wafer by using the ultrahigh-vacuumsputtering equipment. PtMn 20 nm (the antiferromagnetic layer AF 1),CoFe 5 nm (the magnetic layer FM), Ru 1 nm (the non-magnetic layer AC),CoFe 2 nm (the magnetically fixed layer C1), Cu 3 nm (the intermediatelayer B1), CoFe 2 nm (the magnetic recording layer A), Cu 3 nm (theintermediate-layer B-2), CoFe 4 nm (the magnetically fixed layer C2),and PtMn 20 nm (the antiferromagnetic layer AF 2) were formed on thebottom electrode EL 1. Furthermore, the laminated film which consists ofcopper (Cu) and tantalum (Ta) was formed on the cell.

Unidirectional anisotropy was given by annealing this wafer in amagnetic field at 270 degrees C. for 10 hours in a magnetic field vacuumfurnace. One wafer was taken out at this time, the vibrating samplemagnetometer (VSM) performed hysteresis loop measurement of the magneticfield dependence of magnetization, and anti-parallel magnetizationfixing to C1 and C2 was checked. EB resist was applied to this film, EBdrawing was carried out, and the mask with predetermined form was formedin lift-off. Next, the region which is not covered with the mask wasetched by the ion-milling equipment. Here, the amount of etching can begrasped correctly by monitoring the mass of the sputtering particle byusing quadruple mass spectrometer.

The mask was removed after the etching, SiO₂ film was then formedthereon, the surface was smoothed and the face of tantalum (Ta) wasexposed by using the ion milling. The upper electrode was formed on thistantalum face. Thus, the element shown in FIG. 6 was made.

According to the process explained above, the directions of themagnetizations of the magnetically fixed layers C1 and C2 provided atthe upper and lower sides of the magnetic recording layer A can be fixedanti-parallel.

Third Example

The magnetic cell having the structure expressed in FIG. 15 was made asan experiment by the same process as the second example. Also in thisexample, the magnetic cell having the laminated structure which isreversed the upper and lower sides to FIG. 15 was made as an experiment.The material and thickness of each layer are as the following:

-   -   AF1(PtMn:20 nm)/FM1(CoFe:5 nm)/AC(Ru:1 nm)/C1(CoFe:22 nm        )/B1(Cu:3 nm)/A(CoFe:2 nm)/B2(Cu:3 nm)/C2(CoFe:2 nm)/FC(Cu:5        nm)/FM2(CoFe:5 nm)/AF2(PtMn:20 nm)

Also in this structure, the directions of the magnetizations of themagnetically fixed layers C1 and C2 were able to be fixed anti-parallelwith the same process as what was mentioned above about the secondexample.

Fourth Example

Next, samples (sample II through sample V) whose magnetoresistanceeffects are detected easily were formed by giving asymmetry twointermediate layers B1 and B2 as the fourth example of the invention.And the resistance change accompanying the current drive magnetizationreversals were evaluated and studied, compared with the sample (sampleI) whose intermediate layer is symmetrical. The structures of the centerparts of the magnetic cells of samples are as the followings:

Sample I:

-   -   C1(CoFe:10 nm)/B1(Cu:8 nm)/A(CoFe:3 nm)/B2(Cu:8 nm)/C2(CoFe: :10        nm)

Sample II:

C1(CoFe:10 nm)/B1(Cu:8 nm)/A(CoFe:3 nm)/B2(Cu:4 nm)/C2 (CoFe:10 nm)

Sample III:

-   -   C1(CoFe:10 nm)/B1(Cu:8 nm)/A(CoFe:3 nm)/B2(Cu:2        nm)/IE(Al—Cu—O:0.6 nm)/B2(Cu:2 nm)/C2(CoFe:10 nm)

Sample IV:

-   -   C1(CoFe: 10 nm)/B1(Cu: 8 nm)/A(CoFe: 3 nm)/B2 (Al₂O₃—CoFe:3        nm)/C2(CoFe:10 nm)

Sample V:

-   -   C1(CoFe:20 nm)/B1(Cu:8 nm)/A(CoFe:3 nm)/B2(Cu:8 nm)/C2 (Co:2 nm)

In sample I, the intermediate layers B1 and B2 are symmetrical. Insample II, the thickness of the intermediate layers B1 and B2 areasymmetry (FIG. 9). In sample III, the very thin oxide layer (1E) isinserted into the intermediate-layer B2 (FIG. 10). In sample IV, as theintermediate-layer B2, CoFe is precipitated in alumina by simultaneousdeposition of alumina and CoFe, and forms the point contacts of magneticmaterials (FIG. 11). In sample V, the thicknesses and compositions ofthe magnetically fixed layers C1 and C2 are asymmetry (FIG. 8).

In Sample IV, annealing for taking the lattice adjustment at the pointcontacts was carried out. And, the two magnetically fixed layers C1 andC2 were fixed anti-parallel by the same method as the second example, byproviding the PtMn/CoFe/Ru layers on the bottom of the each sample andthe PtMn layer on the top of the each sample.

The changes of the resistances accompanying the magnetization reversalsof the magnetic recording layers A were obtained by sweeping the currentflowing perpendicular to the layer plane. The results were as thefollowings: Sample number rate of resistance change Sample I <0.1%  Sample II 0.4% Sample III 5.0% Sample IV  20% Sample V 0.6%

From this result, it turned out that the efficiency of the detectionbecame high in the samples with asymmetrical, and especially, thesensitivity of the signal detection became higher in the samples inwhich asymmetries were given to the intermediate layer B1 and B2.

The Fifth Example

Next, the magnetic cells which have the same structure as the sample IVof the fourth example were arranged on the substrate and the matrix of32 pieces×32 pieces of the cells was formed as expressed in FIG. 26 asthe fifth example of the invention. The 32 pieces×32 pieces of thematrixes were arranged, and the recording and reproduction medium of 1 M(mega) bit in total was formed. And the magnetic memory, where therecording and reproduction was performed to this recording andreproduction medium, with the 32 pieces×32 pieces of the probes wasmanufactured. That is, one probe corresponds to one set of the matrix inthe magnetic memory of this example.

The probing is performed as expressed in FIG. 30. An XY drive mechanismprovided with the medium can make each probe 200 selecte the cell.However, if the location changes relatively, the drive mechanism 210provided with the probe 200 may select the cell. Moreover, since theprobes 200 were multiplied, each probe was connected with the so-calledword line WL and the so-called bit line BL, and the probes 200 can beselected by specifying the word line WL and the bit line BL.

The recording and reproduction to the magnetic cells 10 was performed bythe current poured from the probes 200 which accessed the magneticcells. Here, by passing the current of plus 1.2 mA and minus 1.2 mA, “0”and “1” signal were written in, respectively. Moreover, forreproduction, the voltage of the cell at the time of passing the currentof 0.5 mA or less was read, and the large and small voltages obtainedwere assigned to “0” and “1.” For comparison, writing-in was performedwith the write-in current of plus 0.5 mA and minus 0.5 mA, and readingwas performed with the reproduction current of 0.4 mA or less. As aresult, when the write-in current was plus 1.2 mA and minus 1.2 mA,writing-in can be performed, but when the write-in current was plus 0.5mA and minus 0.5 mA, writing-in cannot be performed.

The Sixth Example

Next, the example of making the magnetic memory using the magnetic cellwhich has the same structure as the sample III of the fourth examplewill be explained as the sixth example of the invention.

First, the lower bit lines and the transistors were beforehand formed onthe wafer. The magnetic cell array was formed by the same method as theprocess mentioned above about the second example. Then, the word lineswere formed on the magnetic cell array, and the magnetic memory wherethe electrodes of the magnetic cells were connected to the bit lines andthe word lines was formed as expressed in FIG. 31.

The selection of the magnetic cells 10 is performed by specifying theword lines WL and the bit lines BL which were connected with themagnetic cells. That is, the transistors TR are made into ON byspecifying the bit lines BL, and the current is passed through themagnetic cells 10 between the word lines WL and the electrodes. Here, itbecomes possible to record by passing the write-in current Iw largerthan the magnetization reversal current Is which depends on the size,structure, composition, etc. of the magnetic cell through the cell. Theaverage value of Is of the magnetic cell made in this example was 1.8mA. Therefore, when the absolute value of the write-in current is largerthan 1.8 mA, it becomes possible to write in. And, the reading currentmust not exceed 1.8 mA.

In addition, although the probe or the transistor TR was used forselecting the cells in the fifth example and the sixth example, otherswitching elements may be used. It is more desirable to use otherswitching elements which have low resistance at the time of ON.Moreover, diodes may be used.

The Seventh Example

Next, the sample of the following was made by transforming the structureof the magnetic recording layer A of the sample I in the first exampleby the same manufacturing method as the first example as the seventhexample of the invention:

-   -   EL1(Cu)/C1(Co:20 nm)/B1(Cu:10 nm)/A(Co:0.6 nm)/A(Ni:1. 8        nm)/A(Co:0.6 nm)/B2(Cu:6 nm)/C2(Co:20 nm)/EL2(Cu)

That is, the laminated structure of Co(0.6 nm)/Ni(1.8 nm)/Co(0.6 nm) wasadopted as the magnetic recording layer A. About the magnetizationreversal characteristic of this sample, the reversal current was 1.1 mAand the reversal current reduced more compared with the sample I of thefirst example. This is considered because the magnetic energy of themagnetic recording layer A is reduced.

The Eighth Example

Next, the magnetic cell having the structure expressed in FIG. 15 wasmanufactured as the eighth example of the invention. First, two kinds ofmagnetic cells (the sample A10, the sample B10) manufactured in thisexample will be explained.

The sample A10 has the “anti-parallel dual pin structure” which is thestructure where PtMn (20 nm) as the antiferromagnetic layer AF2, Co₉Fe₁(20 nm) as the magnetically fixed layer C2, Cu (4 nm) as theintermediate-layer B2, Co₉Fe₁ (2.5 nm) as the magnetic recording layerA, Cu (6 nm) as the intermediate layer B1, Co₉Fe₁ (4 nm) as themagnetically fixed layer C1, Ru (1 nm) as the non-magnetic layer AC,Co₉Fe₁ (4 nm) as the magnetic layer FM, PtMn (15 nm) as theantiferromagnetic layer AF and the upper electrode which is notillustrated are laminated in this order on the lower electrode which isnot illustrated. In this structure, both of the magnetoresistance effect(MR) through the intermediate layer B1 and that through the intermediatelayer B2 are of the normal type MR. Three kinds of samples with elementsize (60 nm×110 nm, 80 nm×165 nm, and 110 nm×240 nm) were produced.

On the other hand, the sample B10 has the structure where PtMn (20 nm)as the antiferromagnetic layer AF2, Co₉Fe1 (10 nm) as the magneticallyfixed layer C2, Al₂O₃ (0.8 nm) as the intermediate-layer B2, Co₉Fe₁ (2.5nm) as the magnetic recording layer A, Cu (6 nm) as the intermediatelayer B1, Co₉Fe₁ (4 nm) as the magnetically fixed layer C1, Ru (1 nm) asthe non-magnetic layer AC, Co₉Fe₁ (4 nm) as the magnetic layer FM, PtMn(15 nm) as the antiferromagnetic layer AF and the upper electrode whichis not illustrated are laminated in this order on the lower electrodewhich is not illustrated.

In this structure, both of the magnetoresistance effect (MR) through theintermediate layer B1 and that through the intermediate layer B2 were ofthe normal type MR although the materials of the intermediate layer B1and the intermediate layer B2 were different from each other. Threekinds of samples with element size (60 nm×110 nm, 80 nm×165 nm, and 110nm×240 nm) were produced, as the sample A10.

The sample A10 was manufactured with the following procedure.

First, the lower electrode was formed on the wafer.

Then, the wafer was put in to the ultrahigh-vacuum sputtering equipment,and sputtering cleaning of the surface was carried out. Then, themultilayer film having the structure of PtMn(20 nm)/Co₉Fe₁(20 nm)/Cu(4nm)/Co₉Fe₁(2.5 nm)/Cu(6 nm)/Co₉Fe₁(4 nm)/Ru(1 nm) /Co₉Fe₁ (4 nm)/PtMn(15 nm) was deposited. This multilayer film was picked out fromequipment.

Next, the wafer was put in to the vacuum magnetic field furnace, andannealing in the magnetic field was performed at 270 degrees C. for 10hours. Thus the exchange biases were given to the magnetically fixedlayers C1 and C2. Next, the resist was applied and the electron beamexposure was carried out with EB (electron beam) drawing equipment.Then, the mask patterns corresponding to the element sizes mentionedabove were formed. The element was formed by milling these patterns tothe top of the magnetically fixed layer C2 with ion-milling equipment.

The form of the element was set up so that the lateral direction of theelement might become in parallel with the direction of the exchange biasof the magnetically fixed layers C1 and C2. And SiO₂ was embedded in thesurroundings of this element, the top electrode was formed, and themagnetic cell was completed.

The sample B10 was manufactured with the following procedure.

First, the lower electrode was formed on the wafer. Then, the wafer wasput in to the ultrahigh-vacuum sputtering equipment. Then, themultilayer film having the structure of PtMn(20 nm)/CoFe(10 nm)/A1 wasdeposited. Next, Al₂O₃ was formed by introducing oxygen into thesputtering equipment and oxidizing aluminum (Al). Here, the aluminumoxide whose composition is not Al₂O₃ but a composition lacking someoxygen may be formed. This is the same about other examples explained inthis text.

Then, after evacuation of oxygen, the multilayer film having thestructure of PtMn (20 nm)/Co₉Fe₁ (20 nm)/Cu (4 nm)/Co₉Fe₁ (2.5 nm)/Cu (6nm)/CO₉F e₁(4 nm)/Ru(1 nm)/Co₉Fe₁/(4 nm) PtMn (15 nm) was deposited onthe Al₂O₃. And, this multilayer film was picked out from equipment.

Next, the resist was applied and the electron beam exposure was carriedout with EB (electron beam) drawing equipment. Then, the mask patternscorresponding to the element sizes mentioned above were formed. Theelement was formed by milling these patterns to the top of themagnetically fixed layer C2 with ion-milling equipment.

The form of the element was set up so that the lateral direction of theelement might become in parallel with the direction of the exchange biasof the magnetically fixed layers C1 and C2. And SiO₂ was embedded in thesurroundings of this element, the top electrode was formed, and themagnetic cell was completed.

Furthermore, the sample C10, the sample D10, the sample E10, and thesample F10 were produced for comparison. The structures of these samplesare as the followings.

The sample C10 has the structure where PtMn (20 nm) as theantiferromagnetic layer AF2, Co₉Fe₁ (10 nm) as the magnetically fixedlayer C2, TaO1.4 (1 nm) as the intermediate-layer B2, Co₉Fe₁ (2.5 nm) asthe magnetic recording layer A, Cu (6 nm) as the intermediate layer B1,Co₉Fe₁ (4 nm) as the magnetically fixed layer C1, Ru (1 nm) as thenon-magnetic layer AC, Co₉Fe₁ (4 nm) as the magnetic layer FM, PtMn (15nm) as the antiferromagnetic layer AF and the upper electrode arelaminated in this order on the lower electrode. In this structure, themagnetoresistance effect (MR) through TaO_(1.4) of the intermediatelayer B2 was of the reverse type and that through Cu of the intermediatelayer B2 was of the normal type MR. Therefore, this structure wasunsuitable as the magnetic cell of the invention.

The sample D10 has the “single pin structure” which is the structurewhere PtMn (20 nm) as the antiferromagnetic layer AF2, Co₉Fe₁ (20 nm) asthe magnetically fixed layer, Cu (4 nm) as the intermediate-layer,Co₉Fe₁ (2.5 nm) as the magnetic recording layer, and the upper electrodeare laminated in this order on the lower electrode.

The sample E10 has the “single pin structure” which is the structurewhere PtMn (20 nm) as the antiferromagnetic layer AF2, Co₉Fe₁ (20 nm) asthe magnetically fixed layer, Al₂O₃ (0.8 nm) as the intermediate-layer,Co₉Fe₁ (2.5 nm) as the magnetic recording layer, and the upper electrodeare laminated in this order on the lower electrode.

The sample F10 has the structure where Co₉Fe₁ (2.5 nm) as the magneticrecording layer, Cu (6 nm) as the intermediate-layer, Co₉Fe₁ (4 nm) asthe magnetically fixed layer, Ru(1 nm) as the non-magnetic layer, Co₉Fe₁(4 nm) as the magnetic layer, PtMn (15 nm) as the antiferromagneticlayer and the upper electrode are laminated in this order on the lowerelectrode.

The dependencies of the differential resistances on the current weremeasured by passing current of plus 10 mA through minus 10 mA betweenthe upper electrodes and the bottom electrodes of sample A10 with thesize 60 nm×110 nm and the sample B10 with the size 60 nm×110 nm.

FIG. 32 is a graphical representation showing differential resistance ofthe sample A10.

FIG. 33 is a graphical representation showing differential resistance ofthe sample B10.

The direction of the current in case the electron flows from themagnetically fixed layer C2 to the magnetically fixed layer C1 wasdefined as plus. The convex curve was obtained in the sample A10 (FIG.32), and the convex curve was obtained in the sample B10 (FIG. 33). Andboth in the sample A10 and in the sample B10, the region of highresistance and the region of low resistance appeared with the change ofthe current. These results show that the magnetization of the magneticrecording layer A is reversed by the polarity of the current passed inthe magnetic cell and the writing-in of a signal can be carried out.

FIG. 34 is a graphical representation showing the differentialresistivity change obtained by canceling the curves of the backgroundexpressed in FIGS. 32 and 33 and by normalizing the differentialresistances with the regions of low resistances. The results of thesamples D10, E10, and F10 with the same size were also expressed in FIG.34. This figure shows that the currents for the magnetization reversalsof samples A10 and B10 are very smaller than other samples.

In the sample C10, the reversal of the magnetization was not observedwith the current of plus 10 mA through minus 10 mA. That is, it turnedout that the magnetization reversal current of the sample C10 is largerthan 10 mA.

The result shows that the critical current for the magnetizationreversal (Ic) of the samples A10 and B10 are lower than those of thesamples C10, D10, E10, and F10, and the samples A10 and B10 can bewrite-in with lower current.

FIG. 35 is a graphical representation showing the relation between theaverage of the critical magnetization reversal current Ic, and the cellsize. Here, the average of the critical current Ic is a value whichaveraged critical current Ic+ in the case of recording on a lowresistance state from a high resistance state in FIG. 32, and criticalcurrent Ic− in the case of recording on a high resistance state from alow resistance state.

In all samples, the critical currents Ic are mostly in proportion to thesize of the cell. And it turned out that the samples A10 and B10 can bewritten-in with smaller current density than the samples D10, E10, andF10.

The result showed that the structure expressed in FIG. 15 can bewritten-in with low power consumption.

In addition, it was checked that the same tendency as the above isacquired even when MgO, SiO₂, Si—O—N, or SiO₂ or Al₂O₃ which has holesfilled with magnetic materials or conductive metals (Cu, Ag, Au) is usedfor the intermediate-layer B2 of the sample B10.

The Ninth Example

Next, the magnetic cells (the sample A20 and the sample B20) expressedin FIG. 19 and FIG. 20 were manufactured as the ninth example of theinvention.

The sample A20 (FIG. 19) has the structure where PtMn (20 nm), Co₉Fe₁(20 nm) as the magnetically fixed layer C2, Al₂O₃ (0.8 nm) as theintermediate-layer B2, Co₉Fe₁ (1 nm) as the magnetic recording layer A3,Ru (1 nm) as the non-magnetic layer AC, Co₉Fe₁ (1 nm) as the magneticrecording layer A2, Ru (1 nm) as the non-magnetic layer AC, Co₉Fe₁ (1nm) as the magnetic recording layer A1, Cu (6 nm) as the intermediatelayer B1, Co₉Fe₁ (4 nm) as the magnetically fixed layer C1, Ru (1 nm) asthe non-magnetic layer AC, Co₉Fe₁ (4 nm) as the magnetic layer FM, PtMn(15 nm) and the upper electrode are laminated in this order on the lowerelectrode. That is, the sample A20 has the “anti-parallel dual pinstructure”. Three kinds of samples with element size (60 nm×110 nm, 80nm×165 nm, and 110 nm×240 nm) were produced.

On the other hand, the sample B20 (FIG. 20) has the structure where PtMn(20 nm), Co₉Fe₁ (20 nm) as the magnetically fixed layer C2, Cu (4 nm) asthe intermediate-layer B2, Co₉Fe₁ (1.25 nm) as the magnetic recordinglayer A2, Cu (0.3 nm) as the non-magnetic layer FC, Co₉Fe₁ (1.25 nm) asthe magnetic recording layer A1, Cu (6 nm) as the intermediate layer B1,Co₉Fe₁ (4 nm) as the magnetically fixed layer C1, Ru (1 nm) as thenon-magnetic layer AC, Co₉Fe₁ (4 nm) as the magnetic layer FM, PtMn (15nm) and the upper electrode are laminated in this order on the lowerelectrode. That is, the sample B20 also has the “anti-parallel dual pinstructure”. The sample B20 had the same element size as the sample A20.

The sample A20 was manufactured with the following method.

First, the lower electrode was formed on the wafer. Then, the wafer wasput in to the ultrahigh-vacuum sputtering equipment. And, PtMn(20nm)/Co₉Fe₁ (20 nm)/Al was deposited. Next, the oxygen plasma wasgenerated within the sputtering equipment, and Al₂O₃ was formed byoxidizing aluminum. On this Al₂O₃, the multilayer film having thestructure of the Co₉Fe₁(1 nm)/Ru(1 nm)/Co₉Fe₁(1 nm)/Ru(1 nm)/Co₉Fe₁(1nm)/Cu(6 nm )/Co₉Fe₁(4 nm)/Ru/(1 nm)/Co₉Fe₁(4 nm)/PtMn(15 nm) waslaminated. This multilayer film was picked out from equipment.

Next, the resist was applied and the electron beam exposure was carriedout with EB (electron beam) drawing equipment. Then, the mask patternscorresponding to the element sizes mentioned above were formed. Theelement was formed by milling these patterns to the top of the Al₂O₃with ion-milling equipment. The form of the element was set up so thatthe lateral direction of the element might become in parallel with thedirection of the exchange bias of the magnetically fixed layers. AndSiO2 was embedded in the surroundings of this element, the top electrodewas formed, and the magnetic cell was completed.

The sample B20 was manufactured with the same method as the sample A20.

The sample C20, the sample D20 and the sample E20 were produced forcomparison.

FIG. 36 is a schematic diagram showing the cross-sectional structure ofthe sample C20.

The sample C20 has the structure where PtMn (20 nm), Co₉Fe₁ (20 nm) asthe magnetically fixed layer C2, Al₂O₃ (0.8 nm) as theintermediate-layer B2, Co₉Fe₁ (1 nm) as the magnetic recording layer A2,Ru (1 nm) as the non-magnetic layer AC, Co₉Fe₁ (1 nm) as the magneticrecording layer A1, Cu (6 nm) as the intermediate layer B1, Co₉Fe₁ (4nm) as the magnetically fixed layer C1, Ru (1 nm) as the non-magneticlayer AC, Co₉Fe₁ (4 nm) as the magnetic layer FM, PtMn (15 nm) and theupper electrode are laminated in this order on the lower electrode. Thatis, although the sample C20 has the “anti-parallel dual pin structure”,the magnetization of the magnetic layer A1 which is adjacent to theintermediate layers B1 and the magnetization of the magnetic layer A2which is adjacent to the intermediate layers B2 are anti-parallel.Therefore, this structure is unsuitable as the magnetic cell of theinvention.

The sample D20 has the “single pin structure” which is the structurewhere PtMn (20 nm), Co₉Fe₁ (20 nm) as the magnetically fixed layer C1,Al₂O₃ (0.7 nm) as the intermediate-layer B2, Co₉Fe₁ (1 nm) as themagnetic recording layer A3, Ru (1 nm) as the non-magnetic layer AC,Co₉Fe₁ (1 nm) as the magnetic recording layer A2, Ru (1 nm) as thenon-magnetic layer AC, Co₉Fe₁ (1 nm) as the magnetic recording layer A1,and the upper electrode are laminated in this order on the lowerelectrode.

The sample E20 has the “single pin structure” which is the structurewhere PtMn (20 nm), Co₉Fe₁ (20 nm) as the magnetically fixed layer C1,Cu (4 nm) as the intermediate-layer B2, Co₉Fe₁ (1.25 nm) as the magneticrecording layer A2, Cu (0.3 nm) as the non-magnetic layer FC, Co₉Fe₁(1.25 nm) as the magnetic recording layer A1, and the upper electrodeare laminated in this order on the lower electrode.

FIG. 37 is a graphical representation which expresses the dependenciesof the differential resistances on the current in the sample A10, B20,D20 and E20 whose size are 60 nm×110 nm. This figure shows that thecurrents for the magnetization reversals of samples A10 and B10 aresmaller than those of samples D20 and E20. In addition, since the cellof the sample C20 was destroyed electrically before the magnetizationsof the magnetic layers A1 and A2 were reversed, the magnetizationreversal was not observed.

This figure shows that the critical currents for the magnetizationreversals of samples A20 and B20 are smaller than those of samples C20,D20 and E20. And it turned out that the samples A20 and B20 can bewritten-in with smaller current density than the samples C20, D20, andE20.

FIG. 38 is a graphical representation showing the relation between theaverage of the critical magnetization reversal current Ic, and the cellsize. In all samples, the critical currents Ic are mostly in proportionto the size of the cell. And it turned out that the samples A20 and B20can be written-in with smaller current density than the samples D20 andE20.

The result showed that the structures expressed in FIGS. 19 and 20 weresuitable for the magnetic cell which can be written in by low powerconsumption.

In addition, it was checked that the same tendency as the above isacquired even when MgO, SiO2, Si—O—N, or SiO₂ or Al₂O₃ which has holesfilled with magnetic materials or conductive metals (Cu, Ag, Au) is usedfor the intermediate-layer B2 of the sample A20 and theintermediate-layer B2 of the sample B20.

The Tenth Example

Next, the magnetic cells (samples A30 and B30) having the structureexpressed in FIG. 22 was manufactured as the tenth example of theinvention.

The sample A30 has the “anti-parallel dual pin structure” which is thestructure where PtMn (20 nm), Co₉Fe₁ (4 nm) as the magnetic layer FM, Ru(1 nm) as the non-magnetic layer AC, CO₉Fe₁ (4 nm) as the magneticallyfixed layer C2, Cu (3 nm) as the intermediate-layer B2, Co₉Fe₁ (2.5 nm)as the magnetic recording layer A, Cu (6 nm) as the intermediate layerB1, Co₉Fe1 (4 nm) as the magnetically fixed layer C1, Ru (1 nm) as thenon-magnetic layer AC, Co₉Fe₁ (4 nm) as the magnetic layer FM, PtMn (15nm) and the upper electrode are laminated in this order on the lowerelectrode. That is, the sample A30 has the anti-parallel dual pinstructure. Three kinds of samples with element size (60 nm×110 nm, 80nm×165 nm, and 110 nm×240 nm) were produced.

On the other hand, The sample B30 has the “anti-parallel dual pinstructure” which is the structure where PtMn (20 nm), Co₉Fe₁ (4 nm) asthe magnetic layer FM, Ru (1 nm) as the non-magnetic layer AC, Co₉Fe₁ (4nm) as the magnetic layer FM, Ru (1 nm) as the non-magnetic layer AC,Co₉Fe₁ (4 nm) as the magnetically fixed layer C2, Cu (6 nm) as theintermediate-layer B2, Co₉Fe₁ (2.5 nm) as the magnetic recording layerA, Cu (0.8 nm) as the intermediate layer B1, Co₉Fe₁ (4 nm) as themagnetically fixed layer C1, Ru (1 nm) as the non-magnetic layer AC,Co₉Fe1 (4 nm) as the magnetic layer FM, PtMn (15 nm) and the upperelectrode are laminated in this order on the lower electrode. That is,the sample B30 also has the anti-parallel dual pin structure. The sampleB30 had the same element size as the sample A30. In this structure, bothof the magnetoresistance effect (MR) through the intermediate layer B1and that through the intermediate layer B2 were of the normal type MRalthough the materials of the intermediate layer B1 and the intermediatelayer B2 were different from each other.

The sample A30 was manufactured with the following procedure.

First, the SiO₂ layer and the Ta layer were grown up on the lowerelectrode in this order. The resist was applied on it and the maskpattern was drawn with the EB drawing equipment.

Next, the resist in this pattern was removed and the hole correspondingto the element size was made in Ta layer by the ion milling.Furthermore, the slightly bigger hole than the element size was made inSiO2 layer under the Ta layer by reactive ion etching, and the surfaceof the lower electrode was exposed.

Then, the wafer was put in to the ultrahigh-vacuum sputtering equipment,and sputtering cleaning of the surface was carried out.

Then, the multilayer film having the structure of Ru/PtMn (20nm)/Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm)/Ru(1 nm)/CO₉F e₁(4 nm)/Cu(3nm)/Co₉Fe₁(2.5 nm)/Cu (6 nm)/Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm)/PtMn(15nm) was deposited. And, the upper electrode was formed on it. Next, thewafer was put in to the vacuum magnetic field furnace, and annealing inthe magnetic field was performed at 270 degrees C. (centigrade) for 12hours. Thus the exchange biases were given to the magnetically fixedlayers. The form of the element was set up so that the lateral directionof the element might become in parallel with the direction of theexchange bias of the magnetically fixed layers C1 and C2.

The sample B30 was manufactured with the following method.

First, the SiO₂ layer and the Ta layer were grown up on the lowerelectrode in this order. The resist was applied on it and the maskpattern was drawn with the EB drawing equipment. Next, the resist inthis pattern was removed and the hole corresponding to the element sizewas made in Ta layer by the ion milling. Furthermore, the slightlybigger hole than the element size was made in SiO₂ layer under the Talayer by reactive ion etching, and the surface of the lower electrodewas exposed. Then, the wafer was put in to the ultrahigh-vacuumsputtering equipment, and sputtering cleaning of the surface was carriedout. And, Ru/PtMn(20 nm)/Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm)/Ru(1nm)/CO₉F e₁(4 nm)/Cu(6 nm)/Co₉Fe₁(2.5 nm)/Al was grown up on it. Afterintroducing oxygen in the chamber and oxidizing aluminum, the air wasexhausted to the ultrahigh vacuum again. Then, remaining Co₉Fe₁(4nm)/Ru(1 nm)/Co₉Fe₁(4 nm)/PtMn (15 nm) was deposited in this order. And,the upper electrode was formed on it. Next, the wafer was put in to thevacuum magnetic field furnace, and annealing in the magnetic field wasperformed at 270 degrees C. for 12 hours. Thus the exchange biases weregiven to the magnetically fixed layers. The form of the element was setup so that the lateral direction of the element might become in parallelwith the direction of the exchange bias of the magnetically fixedlayers.

Furthermore, the sample C30, the sample D30 and the sample E30 wereproduced for comparison.

The sample C30 has the structure where PtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1nm)/CO₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4 nm) as the magnetically fixedstructure P2, Cu (6 nm) as the intermediate-layer B2, Co₉Fe₁ (2.5 nm) asthe magnetic recording layer A, TaO (1 nm) as the intermediate layer B1,Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁ (4 nm) as the magnetically fixed structureP1, PtMn (15 nm) and the upper electrode are laminated in this order onthe lower electrode. This structure is the anti-parallel dual pinstructure. However, this comparison sample does not suit the invention,because TaO of the intermediate layer B1 is of the reverse type MRthough Cu of the intermediate-layer B2 is of the normal type MR.

The sample D30 has the “single pin structure” which is the structurewhere PtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4nm) as the magnetically fixed structure P2, Cu (3 nm) as theintermediate-layer B2, Co₉Fe₁ (2.5 nm) as the magnetic recording layer Aand the upper electrode are laminated in this order on the lowerelectrode.

The sample E30 has the “single pin structure” which is the structurewhere PtMn (20 nm), PtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4nm)/Ru(1 nm)/CO₉Fe₁(4 nm) as the magnetically fixed structure P2, Al₂O₃(0.8 nm) as the intermediate-layer, Co₉Fe₁ (2.5 nm) as the magneticrecording layer, and the upper electrode are laminated in this order onthe lower electrode.

FIG. 39 is a graphical representation which expresses the relationbetween the differential resistance changes and currents about samplesA30, B30, D30, and E30. The size of the samples are 60 nm×110 nm. Inaddition, since the magnetic cell destroyed the sample C30 electricallybefore magnetization of the magnetic recording layer A was reversed,magnetization reversal was not observed.

The result shows that the critical current for the magnetizationreversal (Ic) of the samples A30 and B30 are lower than those of thesamples C30, D30 and E30, and the samples A30 and B30 can be write-inwith lower current.

FIG. 40 is a graphical representation showing the relation between theaverage of the critical magnetization reversal current Ic, and the cellsize. In all samples, the critical current Ic is mostly in proportion tothe size of the cell. And it turned out that the samples A30 and B30 canbe written-in with smaller current density than the samples C30, D30 andE30.

As explained above, it was checked that the structure expressed in FIG.22 was suitable for the magnetic cell which can be written-in with lowpower consumption.

In addition, it was checked that the same tendency as the above isacquired even when MgO, SiO₂, Si—O—N, or SiO₂ or Al₂O₃ which has holesfilled with magnetic materials or conductive metals (Cu, Ag, Au) is usedfor the intermediate-layer B1 of the sample A30.

The Eleventh Example

Next, the magnetic cells (samples A40 and B40) having the structureexpressed in FIG. 23 and FIG. 24 were manufactured as the eleventhexample of the invention.

The sample A40 (FIG. 23) has the structure where PtMn(20 nm), Co₉Fe₁(4nm)/Ru(1 nm)/CO₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4 nm) as the magneticallyfixed structure P2, Cu (5 nm) as the intermediate-layer B2, Co₉Fe₁(1nm)/Ru (1 nm)/Co₉Fe₁(1 nm)/Ru(1 nm)/Co₉Fe₁ (1 nm) as the magneticrecording layer A, Cu(10 nm) as the intermediate layer B1, Co₉Fe₁(4nm)/Ru(1 nm)/Co₉Fe₁(4 nm) as the magnetically fixed structure P1, PtMn(15 nm) and the upper electrode are laminated in this order on the lowerelectrode. That is, the sample A40 has the anti-parallel dual pinstructure. Three kinds of samples with element size (60 nm×110 nm, 80nm×165 nm, and 110 nm×240 nm) were produced.

On the other hand, the sample B40 has the structure where PtMn (20 nm),Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁/(4 nm) Ru(1 nm)/Co₉Fe₁ (4 nm) as themagnetically fixed structure P2, Al₂O₃ (0.8 nm) as theintermediate-layer B2, Co₉Fe₁(1.25 nm)/Cu (0.3 nm)/Co₉Fe₁(1.25 nm) asthe magnetic recording layer A, Cu (6 nm) as the intermediate layer B1,Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁ (4 nm) as the magnetically fixed structureP1, PtMn (15 nm) and the upper electrode are laminated in this order onthe lower electrode. That is, the sample B40 also had the anti-paralleldual pin structure. In this structure, both of the magnetoresistanceeffect (MR) through the intermediate layer B1 and that through theintermediate layer B2 were of the normal type MR although the materialsof the intermediate layer B1 and the intermediate layer B2 weredifferent from each other. The sample B40 had the same element size asthe sample A30.

The sample A40 was manufactured with the same method as the sample A10.The sample B40 was manufactured with the same method as the sample B10.Furthermore, the sample C40, the sample D40 and the sample E40 wereproduced for comparison.

The sample C40 has the structure where PtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1nm)/CO₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4 nm) as the magnetically fixedstructure P2, Cu (5 nm) as the intermediate-layer B2, Co₉Fe₁(1 nm)/Ru(1nm)/Co₉Fe₁(1 nm) as the magnetic recording layer A, Cu (10 nm) as theintermediate layer B1, Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm) as themagnetically fixed structure P1, PtMn (15 nm) and the upper electrodeare laminated in this order on the lower electrode. Although thisstructure is the anti-parallel dual pin structure, the magnetization ofthe magnetic recording layer A which is adjacent to the intermediatelayers B1 and the magnetization of the magnetic recording layer A whichis adjacent to the intermediate layers B2 are anti-parallel. Therefore,this structure is different from the structure of the invention.

The sample D40 has the single pin structure which is the structure wherePtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4 nm)as the magnetically fixed structure, Cu (6 nm) as the intermediate-layerB2, Co₉Fe₁(1 nm)/Ru(1 nm)/Co₉Fe₁(1 nm)/Ru(1 nm)/Co₉Fe₁(1 nm) as themagnetic recording layer A and the upper electrode are laminated in thisorder on the lower electrode.

The sample E40 has the single pin structure which is the structure wherePtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4 nm)as the magnetically fixed structure, Al₂O₃ (0.7 nm) as theintermediate-layer B2, Co₉Fe₁(1.25 nm)/Cu(0.3 nm)/Co₉Fe₁(1.25 nm)as themagnetic recording layer A and the upper electrode are laminated in thisorder on the lower electrode.

FIG. 41 is a graphical representation which expresses the relationsbetween the differential resistance changes and currents about samplesA40, B40, D40, and E40. Here, the size of the cells is 60 nm×110 nm.FIG. 41 shows that the current at which the magnetizations of samplesA40 and B40 are reversed are smaller than the samples D40 and E40. Inthe sample C40, since the cells were broken electrically before thereversal of the magnetization of the magnetic recording layer A, themagnetization reversal was not observed.

The result shows that the critical current for the magnetizationreversal (Ic) of the samples A40 and B40 are lower than those of thesamples C40, D40 and E40, and the samples A40 and B40 can be write-inwith lower current.

FIG. 42 is a graphical representation showing the relation between theaverage of the critical magnetization reversal current Ic, and the cellsize. In all samples, the critical current Ic is mostly in proportion tothe size of the cell. And it turned out that the samples A40 and B40 canbe written-in with smaller current density than the samples C40, D40 andE40.

As explained above, it was checked that the structures expressed in FIG.23 and FIG. 24 were suitable for the magnetic cell which can bewritten-in with low power consumption.

In addition, it was checked that the same tendency as the above isacquired even when MgO, SiO₂, Si—O—N, or SiO₂ or Al₂O₃ which has holesfilled with magnetic materials or conductive metals (Cu, Ag, Au) is usedfor the intermediate-layer B2 of the sample A40 and the intermediatelayer B2 of the sample B40.

The Twelfth Example

Next, the magnetic cells (samples A50 and B50) having the structuresexpressed in FIG. 21 and FIG. 25 were manufactured as the twelfthexample of the invention.

The sample A50 (FIG. 21) has the “anti-parallel dual pin structure”which is the structure where PtMn (20 nm), Co₉Fe₁ (20 nm) as themagnetically fixed layer, Cu (6 nm) as the intermediate-layer B2,CO₉Fe₁(0.8 nm)/NiFe(0.8 nm)/Co₉Fe₁ (0.8 nm) as the magnetic recordinglayer A, Al₂O₃ (1 nm) as the intermediate layer B1, Co₉Fe₁(4 nm)/Ru(1nm)/Co₉Fe₁ (4 nm) as the magnetically fixed structure P1, PtMn (15 nm)and the upper electrode are laminated in this order on the lowerelectrode. Three kinds of samples with element size (60 nm×110 nm, 80nm×165 nm, and 110 nm×240 nm) were produced.

On the other hand, the sample B50 (FIG. 21) has the “anti-parallel dualpin structure” which is the structure where PtMn (20 nm), Co₉Fe₁(4nm)/Ru(1 nm)/Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm) as the magneticallyfixed layer, Cu (6 nm) as the intermediate-layer B2, Co₉Fe₁(0.8nm)/NiFe(0.8 nm)/Co₉Fe₁ (0.8 nm) as the magnetic recording layer A,Al₂O₃ (1 nm) as the intermediate layer B1, Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm) as the magnetically fixed structure P1, PtMn (15 nm) and theupper electrode are laminated in this order on the lower electrode. Thesample B50 had the same element size as the sample A50.

In this structure, both of the magnetoresistance effect (MR) through theintermediate layer B1 and that through the intermediate layer B2 were ofthe normal type MR although the materials of the intermediate layer B1and the intermediate layer B2 were different from each other.

The sample A50 was manufactured with the following procedure.

First, the SiO₂ layer and the Ta layer were grown up on the lowerelectrode in this order. The resist was applied on it and the maskpattern was drawn with the EB drawing equipment. Next, the resist inthis pattern was removed and the hole corresponding to the element sizewas made in Ta layer by the ion milling. Furthermore, the slightlybigger hole than the element size was made in SiO₂ layer under the Talayer by reactive ion etching, and the surface of the lower electrodewas exposed.

Then, the wafer was put in to the ultrahigh-vacuum sputtering equipment,and sputtering cleaning of the surface was carried out. Then, themultilayer film having the structure of Ru/PtMn(20 nm)/Co₉Fe₁(20nm)/Cu(6 nm)/Co₉Fe₁(0.8 nm)/NiFe(0.8 n m)/Co₉Fe₁(0.8 nm)/Al wasdeposited. Next, oxygen was introduced in the chamber and the aluminumat the surface was oxidized. And, the air was evacuated to the ultrahighvacuum. Then, remaining Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm)/PtMn (15 nm)was deposited, and the upper electrode was formed.

Next, the wafer was put in to the vacuum magnetic field furnace, andannealing in the magnetic field was performed at 270 degrees C. for 12hours. Thus the exchange biases were given to the magnetically fixedlayers. The form of the element was set up so that the lateral directionof the element might become in parallel with the direction of theexchange bias of the magnetically fixed layers C1 and C2.

The sample B50 was produced with the same method as A10.

Furthermore, the sample C50 and the sample D50 were produced forcomparison.

The sample C50 has the “single-pin structure” which is the structurewhere Co₉Fe₁(12 nm) as the magnetically fixed layer C2, Cu (6 nm) as theintermediate-layer B2, Co₉Fe₁(0.8 nm)/NiFe(0.8 nm)/Co₉Fe₁(0.8 nm) as themagnetic recording layer A and the upper electrode are laminated in thisorder on the lower electrode.

The sample D30 has the “single-pin structure” which is the structurewhere PtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4nm) as the magnetically fixed structure P2, Cu (6 nm) as theintermediate-layer B2, Co₉Fe₁(0.8 nm)/NiFe(0.8 nm)/Co₉Fe₁ (0.8 nm) asthe magnetic recording layer A and the upper electrode are laminated inthis order on the lower electrode.

FIG. 43 is a graphical representation which expresses the relationsbetween the differential resistance changes and currents about samplesA50, B50, C50, and D50. The size of the samples is 60 nm×110 nm. Theresult shows that the critical currents for the magnetization reversal(Ic) of the samples A50 and B50 are lower than those of the samples C50,D50 and E50, and the samples A30 and B30 can be written-in with lowercurrent.

FIG. 44 is a graphical representation showing the relation between theaverage of the critical magnetization reversal current Ic, and the cellsize. In all samples, the critical current Ic is mostly in proportion tothe size of the cell. And it turns out that the samples A50 and B50 canbe written-in with smaller current density than the samples D50 and E50.

As explained above, it was checked that the structures expressed in FIG.21 and FIG. 25 was suitable for the magnetic cell which can bewritten-in with low power consumption.

In addition, it was checked that the same tendency as the above isacquired even when MgO, SiO₂, Si—O—N, or SiO₂ or Al₂O₃ which has holesfilled with magnetic materials or conductive metals (Cu, Ag, Au) is usedfor the intermediate-layer B1 or B2 of the samples A50 and the sampleB50.

The Thirteenth Example

Next, the samples provided the structure where three layers in which theantiferromagnetic couplings are carried out are adopted as themagnetically fixed structure were compared with the samples provided thestructure where one layer is adopted as the magnetically fixed layer asthe thirteenth example of the invention. That is, the magnetic cellswhich have the structures expressed in FIG. 15 (samples A60 and E60),FIG. 14 (samples B60 and F60), FIG. 22 (samples C60 and G60), and FIG.45 (samples D60 and H60) were created.

The sample A60 (FIG. 15) has the “anti-parallel dual pin structure”which is the structure where PtMn (20 nm), Co₉Fe₁ (4 nm) as themagnetically fixed layer C2, Al₂O₃ (0.8 nm) as the intermediate-layerB2, Co₉Fe₁ (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as theintermediate layer B1, Co9Fe1(4 nm)/Ru(1 nm)/Co9Fe1(4 nm) as themagnetically fixed structure P1, PtMn (15 nm) as the antiferromagneticlayer AF and the upper electrode are laminated in this order on thelower electrode.

The sample B60 (FIG. 14) has the “anti-parallel dual pin structure”which is the structure where PtMn (20 nm), Co₉Fe₁ (4 nm) as themagnetically fixed layer C2, Al₂O₃ (0.8 nm) as the intermediate-layerB2, Co₉Fe₁ (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as theintermediate layer B1, Co9Fe1 (4 nm) as the magnetically fixed layer C1,PtMn (15 nm) as the antiferromagnetic layer AF and the upper electrodeare laminated in this order on the lower electrode.

The sample C60 (FIG. 22) has the “anti-parallel dual pin structure”which is the structure where PtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1nm)/CO₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁ (4 nm) as the magnetically fixedstructure P2, Al₂O₃ (0.8 nm) as the intermediate-layer B2, Co₉Fe₁ (2.5nm) as the magnetic recording layer A, Cu (6 nm) as the intermediatelayer B1, Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁ (4 nm) as the magnetically fixedstructure P1, PtMn (15 nm) and the upper electrode are laminated in thisorder on the lower electrode.

The sample D60 (FIG. 45) has the “anti-parallel dual pin structure”which is the structure where PtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe₁ (4 nm) as the magnetically fixed structure P2,Al₂O₃ (0.8 nm) as the intermediate-layer B2, Co₉Fe₁(2.5 nm) as themagnetic recording layer A, Cu (6 nm) as the intermediate layer B1,Co₉Fe₁(4 nm) as the magnetically fixed layer C1, PtMn (15 nm) and theupper electrode are laminated in this order on the lower electrode.

The sample E60 (FIG. 15) has the “anti-parallel dual pin structure”which is the structure where PtMn (20 nm), Co₉Fe₁ (4 nm) as themagnetically fixed layer C2, Al₂O₃ (0.8 nm) as the intermediate-layerB2, Co₉Fe₁ (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as theintermediate layer B1, Co₉Fe₁(6 nm) as the magnetically fixed layer C1,PtMn (15 nm) as the antiferromagnetic layer AF and the upper electrodeare laminated in this order on the lower electrode.

The sample F60 (FIG. 14) has the “anti-parallel dual pin structure”which is the structure where PtMn (20 nm), Co₉Fe₁ (4 nm) as themagnetically fixed layer C2, Al₂O₃ (0.8 nm) as the intermediate-layerB2, Co₉Fe₁ (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as theintermediate layer B1, Co₉Fe₁ (6 nm) as the magnetically fixed layer C1,PtMn (15 nm) as the antiferromagnetic layer AF and the upper electrodeare laminated in this order on the lower electrode.

The sample G60 (FIG. 22) has the “anti-parallel dual pin structure”which is the structure where PtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1 nm)/CO₉Fe(4 nm)/Ru(1 nm)/CO₉Fe₁ (3 nm) as the magnetically fixed structure P2,Al₂O₃ (0.8 nm) as the intermediate-layer B2, Co₉Fe₁ (2.5 nm) as themagnetic recording layer A, Cu (6 nm) as the intermediate layer B1,Co₉Fe₁(5 nm)/Ru(1 nm)/Co₉Fe₁ (6 nm) as the magnetically fixed structureP1, PtMn (15 nm) and the upper electrode are laminated in this order onthe lower electrode.

The sample H60 (FIG. 45) has the “anti-parallel dual pin structure”which is the structure where PtMn (20 nm), Co₉Fe₁(4 nm)/Ru(1nm)/Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(3 nm) as the magnetically fixedstructure P2, Al₂O₃ (0.8 nm) as the intermediate-layer B2, Co₉Fe₁ (2.5nm) as the magnetic recording layer A, Cu (6 nm) as the intermediatelayer B1, Co₉Fe₁(6 nm) as the magnetically fixed layer C1, PtMn (15 nm)and the upper electrode are laminated in this order on the lowerelectrode.

In all samples, the element size is 50 nm×120 nm. About samples A60through H60, the average values of the critical current Ic obtained fromthe dependencies of the differential resistances on the current werecalculated.

The result is as the following: Sample Average of the critical currentIc (mA) A60 0.36 B60 0.60 C60 0.29 D60 0.54 E60 0.32 F60 0.55 G60 0.28H60 0.53

In all samples of the invention, Ic were low. Comparing the sample A60with the sample B60, it turns out that the critical current Ic of thecell (FIG. 15) provided the magnetically fixed structure P1 whosemagnetizations are anti-parallel is smaller than that of the cell (FIG.14) provided one layer as the upper magnetically fixed layer C1.Similarly, comparing the sample C60 (FIG. 22) with the sample D60 (FIG.45), comparing the sample E60 (FIG. 15) with the sample F60 (FIG. 14)and comparing the sample G60 (FIG. 22) with the sample H60 (FIG. 45), italso turns out that the critical current Ic of the cell (FIG. 15 andFIG. 22) provided the magnetically fixed structure P1 whosemagnetizations are anti-parallel is smaller than that of the cell (FIG.14 and FIG. 45) provided one layer as the upper magnetically fixed layerC1.

That is, it has checked that it was effective for reducing the criticalcurrent Ic to use the laminated structure of the magnetic layer andnon-magnetic layer which carried out anti-parallel couplings as themagnetically fixed structure. In addition, the same effect was acquiredwhen the material of intermediate-layer B-2 was except an insulator.Moreover, the same effect was also acquired when the magnetic recordinglayer A was constituted by the three magnetic layers.

The Fourteenth Example

Next, as the fourteenth example of the invention, the cells having thestructures explained below were produced. The sizes of the cells were 60nm×130 nm. And the critical currents Ic of these cells were acquired.The laminated structures of the samples of this example from the viewpoints of the lower electrodes, and the measurement results of criticalcurrents Ic are expressed in the following. This result shows that themagnetic cell which can be written-in with low power consumption can beoffered, according to the invention.

Sample A70:

-   -   AF2(PtMn:20 nm)/C2(CO₉Fe₁:20 nm)/B2(MgO:1 nm)/A(CO₉Fe₁: 2.5        nm)/B1(Cu:6 nm)/C1(Co₉Fe₁:5 nm)/AC (Ru:1 nm)/FM(Co₉Fe₁: 5 nm)        /AF1(PtMn:15 nm)    -   Ic average: 0.67 mA

sample A71:

-   -   AF2(PtIrMn:17 nm)/FM(CO₉Fe₁:4 nm)/AC(Ru:1 nm)/C2(CO₉Fe₁:4        nm)/B2(MgO:1 nm)/A3(Co₉Fe₁:0.8 nm)/A2 (NiFe:0.8 nm)/A1(CO₉F        e₁:0.8 nm)/B1(Cu:6 nm)/C1(Co₉Fe₁:4 nm)/AF1 (PtIrMn:17 nm)    -   Ic average: 0.41 mA

Sample A72:

-   -   AF2 (PtMn:20 nm)/C2(Co₉Fe₁:20 nm)/B-2 (Si—O—N:1 nm)/A3        (Co₉Fe₁:0.8 nm)/A2(NiFe:0.8 nm)/A1(Co₉Fe₁:0.8 nm)/B1(Cu:6        nm)/C1(Co₉Fe₁:4 nm)/AC(Ru:1 nm)/FM(Co₉Fe₁:4 nm)/AF2(PtMn:15 nm)    -   Ic average: 0.67 mA

Sample A73:

-   -   AF2(PtMn:15 nm)/C2(Co₉Fe₁:20 nm)/B-2(SiO₂ with holes: 5        nm)/A(Co₉Fe₁: 3 nm)/B1 (Cu: 8 nm)/C1 (Co₉Fe₁:4 nm)/AC(Ru:1        nm)/FM (Co₉Fe₁:4 nm)/AF1(PtMn:15 nm)    -   Ic average: 0.59 mA

sample A74:

-   -   AF2 (IrMn:19 nm)/C2(CO₈Fe₂:4 nm)/B2(MgO: 1 nm)/A3 (Fe₈CO₂: 0.8        nm)/A2(NiFeCo:0.8 nm)/A1(CO₈Fe₂:0.8 nm)/B1 (Cu: 6 nm)/C1(Co        ₈Fe₂:4 nm)/AC(Ru:1 nm)/FM(CO₈Fe₂:4 nm)/AF1(IrMn:19 nm)    -   Ic average: 0.82 mA

sample A75:

-   -   AF2(PtMn:20 nm)/C2(Co₉Fe₁:20 nm)/B2(Cu: 6 nm)/A3(Co₉Fe₁: 0.8        nm)/A2(NiFe:0.8 nm)/A1(Co₉Fe₁:0.8 nm)/B1(Cu:0.6 nm)/B1(Al 203        with holes filled with Cu:3 nm)/B1(Cu: 0.6 nm)/C1(Co₉Fe₁: 4        nm)/AC (Ru:1 nm)/FM (Co₉Fe₁: 4 nm)/AF1(PtMn:1 5 nm)    -   Ic average: 0.57 mA

Sample A76:

-   -   AF2(Ptn:10 nm)/FM(Co₉Fe₁:4 nm)/AC(Ru:1 nm)/C2(Co₉Fe₁:2 0        nm)/B2(MgO:0.8 nm)/A(Co₉Fe₁:3 nm)/B1(Cu: 6 nm)/C1(Co₉Fe₁: 5 nm)        /AF1(PtMn:15 nm)    -   Ic average: 0.83 mA

sample A77:

-   -   AF2(PtMn:15 nm)/FM(Co₉Fe₁:4 nm)/AC(Ru:1 nm)/C2(Co₉Fe₁:4        nm)/B2(Al₂O₃:0.7 nm)/A3(Co₉Fe₁:0.6 nm)/A2(NiFe: 1 nm)/A1(Co₉Fe        ₁:0.6 nm)/B1(Cu:8 nm)/C1(Co₉Fe₁: 5 nm)/AF1(PtMn:15 nm)    -   Ic average: 0.78 mA

Sample A78:

-   -   AF2(PtIrMn:15 nm)/C2(Co₉Fe₁:20 nm)/B2 (Al₂O₃ with holes:3        nm)/A(Co₉Fe₁:3.6 nm)/B1(Cu:6 nm)/C1 (Co₉Fe₁: 5 nm)/AC (Ru :1        nm)/FM(Co₉Fe₁:5 nm)/AF1(PtIrMn: 15 nm)    -   Ic average: 0.90 mA

sample A79:

-   -   AF2(PtMn:20 nm)/FM(Co₉Fe₁:5 nm)/C(Ru:1 nm)/C2(Co₉Fe₁:5n        m)/B2(Cu:6 nm)/A3(Co₉Fe₁:0.6 nm)/A2(NiFe:1.2 nm)/A1(Co₉Fe₁:0. 6        nm)/B1(Si—N—O: 1 nm)/C1(Co₉Fe₁:5 nm)/AF1(PtMn:15 nm)    -   Ic average: 0.78 mA

The Fifteenth Example

Next, the magnetic cell which has the combination of the reverse typemagnetoresistance effect and the reverse type magnetoresistance effectand the magnetic cell which has the combination of the reverse typemagnetoresistance effect and the normal type magnetoresistance effectwere created and evaluated, as the fifteenth example of the invention.

FIG. 46 is a schematic diagram showing the cross-sectional structure ofthe magnetic cell manufactured in this example. In this magnetic cell(sample X), the magnetoresistance effect between the magnetically fixedlayer C1 and the recording layer A through the intermediate layer B1 isof the reverse type, and the magnetoresistance effect between themagnetically fixed layer C2 and the recording layer A through theintermediate layer B2 is also of the reverse type.

FIG. 47 is a schematic diagram showing the cross-sectional structure ofthe magnetic cell of the comparative example. In this magnetic cell(sample Y), the magnetoresistance effect between the magnetically fixedlayer C1 and the recording layer A through the intermediate layer B1 isof the reverse type, and the magnetoresistance effect between themagnetically fixed layer C2 and the recording layer A through theintermediate layer B2 is of the normal type. The laminated structures ofthese samples are as follows:

Sample X:

-   -   Fe₃O₄/SrTiO₃(STO)/La_(0.7)Sr_(0.3)MnO₃ (LSMO)/SrTiO₃/CoFe/PtMn

Sample Y:

-   -   Fe₃O₄/SrTiO₃(STO)/La_(0.7)Sr_(0.3)MnO₃(LSMO)/SrTiO₃(STO)/La_(0.7)        Sr_(0.3)MnO₃ (LSMO)/CoFe/PtMn

Both resistance of Fe₃O₄/STO/LSMO and resistance of LSMO/STO/CoFe becamelarge as the magnetic field was applied thereto.

That is, the resistance when the magnetizations of two magnetic layersare parallel became larger than that when the magnetizations of twomagnetic layers are anti-parallel. That is, it has checked beforehandthat the reverse type magnetoresistance effect was shown.

And, the resistance of LSMO/SrTiO₃/LSMO/CoFe became small as themagnetic field was applied threreto. That is, the resistance when themagnetizations of two magnetic layers are parallel became smaller thanthat when the magnetizations of two magnetic layers are anti-parallel.That is, it has checked beforehand that the normal typemagnetoresistance effect was shown.

A single crystal substrate is used for Fe304 which constitutes the lowermagnetically fixed layer C2 and is also used as the lower electrode. STOand a LSMO film were grown up on the heating substrate using pulsedlaser deposition. And the sample was conveyed to the sputtering chamberwithout exposure to the air, the CoFe layer and the PtMn layer wereformed, and Ta layer was formed as the upper electrode. The substratewas introduced into the annealing furnace in a magnetic field afterforming these films. And exchange bias was introduced into the CoFelayer which was adjacent to PtMn, and magnetizations were fixed to onedirection.

Next, the element was formed deleting to the lower STO layer by usingmicro fabrication technique. The element bonded to the Fe₃O₄ substratewas put on the one side of the magnet with picture frame shape, and themagnetization direction of Fe₃O₄ was fixed anti-parallel to themagnetization direction of the upper magnetically fixed layer C1.

Thus, the magnetoresistance was measured by passing the current at 77Kbetween the lower electrode of and the upper electrode of sample X andsample Y. The magnetoresistance of sample X was 17% and themagnetoresistance of sample Y was 50%.

Next, the dependencies of the differential resistances on the currentwere measured in 77K. In the case of sample X, gentle changes in thedifferential resistance which corresponded to the change in themagnetoresistance were observed at around plus 60 mA and minus 55 mA,respectively.

On the other hand, in the case of sample Y, any significant change inthe differential resistance was not observed in the current range fromminus 100 mA to plus 100 mA.

As explained above, the magnetic cell (sample X) in which both of themagnetoresistance effect between the magnetically fixed layer C1 and therecording layer A through the intermediate layer B1 and themagnetoresistance effect between the magnetically fixed layer C2 and therecording layer A through the intermediate layer B2 are of the reversetype can be written-in with low power consumption.

On the other hand, the magnetic cell (sample Y) in which themagnetoresistance effect between the magnetically fixed layer C1 and therecording layer A through the intermediate layer B1 is of the reversetype and the magnetoresistance effect between the magnetically fixedlayer C2 and the recording layer A through the intermediate layer B2 isof the normal type can not be written-in with low power consumption.That is, the effect of reducing the writing-in current can not beobtained.

The Sixteenth Example

Next, the magnetic cells (samples XX) having the structure expressed inFIG. 14 was manufactured as the sixteenth example of the invention.

Moreover, for comparison with the sample XX, the magnetic cell (sampleYY) provided two magnetically fixed layers C1 and C2 whose magnetizationdirections are parallel was manufactured, as expressed in FIG. 48.

First, the magnetic cells (Sample XX, sample YY) manufactured in thisexample will be explained.

The sample XX (FIG. 14) has the “anti-parallel dual pin structure” whichis the structure where PtMn (15 nm) as the antiferromagnetic layer AF2,Co₉Fe₁ (12 nm) as the magnetically fixed layer C2, Cu (3 nm) as theintermediate-layer B2, Co₉Fe₁ (2.5 nm) as the magnetic recording layerA, Cu (6 nm) as the intermediate layer B1, Co₉Fe₁ (6 nm) as themagnetically fixed layer C1, IrMn (15 nm) as the antiferromagnetic layerAF1 and the upper electrode which is not illustrated are laminated inthis order on the lower electrode which is not illustrated.

On the other hand, the sample YY (FIG. 48) has the structure where PtMn(15 nm) as the antiferromagnetic layer AF2, Co₉Fe₁ (12 nm) as themagnetically fixed layer C2, Cu (4 nm) as the intermediate-layer B2,Co₉Fe₁ (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as theintermediate layer B1, Co₉Fe₁ (6 nm) as the magnetically fixed layer C1,PtMn (15 nm) as the antiferromagnetic layer AF1 and the upper electrodewhich is not illustrated are laminated in this order on the lowerelectrode which is not illustrated.

The two magnetically fixed layers C1 and C2 of the sample XX were fixedanti-parallel, and those of the sample YY were fixed parallel with thefollowing method.

The sample XX was produced with the following procedure.

First, the lower electrode was formed on the wafer. Then, the wafer wasput in to the ultrahigh-vacuum sputtering equipment, and sputteringcleaning of the surface was carried out. Then, the multilayer filmhaving the structure of PtMn (15 nm)/Co₉Fe₁(12 nm)/Cu(4 nm)/Co₉Fe₁(2.5nm)/Cu(6 nm)/CO₉F e₁(6 nm)/IrMn (15 nm) was deposited. This multilayerfilm was picked out from equipment.

Next, the wafer was put in to the vacuum magnetic field furnace, andannealing in the magnetic field was performed at 270 degrees C. for 10hours. Then, the exchange biases having the same directions were givento the magnetically fixed layers C1 and C2. Then, the polarity of themagnetic field was reversed after heating down to 240 degrees C. Then,the exchange bias having the reverse direction to the magnetizationdirection of the magnetically fixed layers C2 were given to themagnetically fixed layers C1 by annealing in the magnetic field for onehour.

Next, the resist was applied and the electron beam exposure was carriedout with EB (electron beam) drawing equipment. Then, the mask patternscorresponding to the element sizes mentioned above were formed.

The element was formed by milling these patterns to the top of themagnetically fixed layer C2 with ion-milling equipment.

The form of the element was set up so that the lateral direction of theelement might become in parallel with the direction of the exchange biasof the magnetically fixed layers C1 and C2. And SiO₂ was embedded in thesurroundings of this element, the top electrode was formed, and themagnetic cell was completed.

On the other hand, the sample YY was manufactured with the followingprocedure.

First, the lower electrode was formed on the wafer. Then, the wafer wasput in to the ultrahigh-vacuum sputtering equipment, and sputteringcleaning of the surface was carried out. Then, the multilayer filmhaving the structure of PtMn(15 nm)/Co₉Fe₁(12 nm)/Cu(4 nm)/Co₉Fe₁(2.5nm)/Cu(6 nm)/CO₉F e₁(6 nm)/PtMn(15 nm) was deposited. This multilayerfilm was picked out from equipment.

Next, the wafer was put in to the vacuum magnetic field furnace, andannealing in the magnetic field was performed at 270 degrees C. for 10hours. Then, the exchange biases were given to the magnetically fixedlayers C1 and C2. Next, the resist was applied and the electron beamexposure was carried out with EB (electron beam) drawing equipment.Then, the mask patterns corresponding to the element sizes mentionedabove were formed. The element was formed by milling these patterns tothe top of the magnetically fixed layer C2 with ion-milling equipment.

The form of the element was set up so that the lateral direction of theelement might become in parallel with the direction of the exchange biasof the magnetically fixed layers C1 and C2. And SiO₂ was embedded in thesurroundings of this element, the top electrode was formed, and themagnetic cell was completed.

The dependencies of the differential resistances on the currents weremeasured by passing the current between the upper electrode and thelower electrode about two kinds element sizes 50 nm×110 nm and 80 nm×160nm. And the average values of the critical current Ic were calculated.The result is as the following: Sample Size Average of critical currentIc (mA) XX 50 nm × 110 nm 0.70 XX 80 nm × 160 nm 1.83 YY 50 nm × 110 nm9.22 YY 80 nm × 160 nm Not reversed

It turns out that the “anti-parallel dual pin structure” expressed inFIG. 14 can be written-in with low current, although the effect of thereduction of the reversal current can not be attained in the dual pinstructure as the reference sample whose magnetization directions of thetwo magnetically fixed layers are parallel. In addition, it was checkedthat the same tendency as the above is acquired even when MgO, SiO₂,Si—O—N, or SiO₂ or Al₂O₃ which has holes filled with magnetic materialsor conductive metals (Cu, Ag, Au) is used for the intermediate-layer B2of the sample XX.

The Seventeenth Example

Next, the magnetic memory (Magnetic Random Access Memory:MRAM) which hasthe magnetic cell of the invention and MOSFET (Metal-Semicoductor-OxideField Effect Transistor) will be explained as the seventeenth example ofthe invention.

FIG. 49A through FIG. 49D are schematic diagrams showing thecross-sectional structures of the memory cells of the magnetic memoriesof this example. In these figures, the cases where the magnetic cellincludes a normal type MR and a normal type MR are shown. The arrows inthe figures show the electron flow.

This magnetic memory has the equivalent circuit expressed in FIG. 31except that the assignment of the bit lines and the word lines isreversed.

That is, this memory cell has the magnetic cell 10 of the invention andMOSFET (TR).

These memory cells are provided in a matrix fashion, and each cell isconnected to the bit line BL and the word line WL.

The selection of a specific memory cell is performed by selecting thebit line BL connected to the memory cell, and the word line WL connectedto the gate G of MOSFET (TR).

FIG. 49A and FIG. 49B are the schematic diagrams for explaining write-inoperation.

That is, the writing to the magnetic cell 10 is performed by passing thecurrent to the magnetic cell 10 through the bit line BL.

Signals are written in the magnetic recording layer A by passingwrite-in current Iw larger than magnetization reversal current Ic.

The magnetization of the magnetic recording layer is written in so thatthe magnetization of the magnetic recording layer may be the samedirection to the magnetization direction of the magnetically fixed layerthough which the electron passes first.

Therefore, corresponding to the polarity of write-in current Iw, thedirection of magnetization of the magnetic recording layer A changes.

With this mechanism, “0” can be written in as expressed in FIG. 49A, and“1” can be written in as expressed in FIG. 49B.

In addition, the assignment of “0” and “1” may be reversed.

FIG. 49C and FIG. 49D are the schematic diagrams for explaining read-outoperation.

The read-out is detected by the quantity of resistance of the magneticcell 10.

Although either direction of the sense current Ir will be, the quantityof the sense current Ir needs to be made smaller than the magnetizationreversal current IC.

In the structure expressed in FIG. 49A through FIG. 49D, in the casewhere the resistance through the upper intermediate layer B1 is largerthan that through the lower intermediate layer B2, when the sensecurrent Ir is passed through the magnetic cel 10 shown in FIG. 49C theresistance is large and when the sense current Ir is passed through themagnetic cel 10 shown in FIG. 49D the resistance is small.

The read-out is carried out by detecting the difference between theseresistances as voltage.

The case expressed in FIG. 49C may be assigned with “0” and the caseexpressed in FIG. 49D may be assigned with “1”, for example.

However, the assignment of “0” and “1” may be reversed.

Hereafter, referring to drawings, the magnetic memory of this examplewill now be described in detail.

The lower wiring and the lower electrode were formed on the wafer inwhich MOSFET was formed.

Then, the multilayer film of Ta(5 nm)/Ru(2 nm)/PtMn (15 nm)/Co₉Fe₁(15nm)/Al₂O₃(0.8 nm)/Co₉Fe₁(0.6 nm)/NiFe(1.2 nm) /Co₉Fe₁(0.6 nm)/Cu(6nm)/Co₉Fe₁(4 nm)/Ru (1 nm)/Co₉Fe₁ (4 nm)/PtM n (15 nm) was grown up onit and annealed in the magnetic field in vacuum to introduce theexchange bias to fix the magnetization directions of the magnetic fixedlayers.

And a micro fabrication process was performed to this multilayer film,and thus, the element was formed. In the process, the ion milling wasstopped at the top of the Al₂O₃ layer of the intermediate-layer B2, asexpressed in FIG. 50. This is because the etched material may bedeposited on the side wall of the Al₂O₃ which is to be the intermediatelayer B2 in the ion milling process, and the re-deposited material maycause a current leakage.

In contrast, if Al₂O₃ layer of the intermediate layer B2 is not etchedby the ion milling as shown in FIG. 50, the current leakage by there-deposition can be prevented.

After performing a pattering process to the laminated structure of themagnetic cell, wirings were formed on the upper part thereof and themagnetic memory of the matrix fashion of 2×2 was produced.

In the obtained magnetic memory, any one of the memory cells can beselected by selecting one of the word lines WL and one of the bit linesBL.

Test was performed by setting the write-in current at three levels of(1) a pulse current of plus-or-minus 0.15 mA of 20 milliseconds, (2) apulse current of plus-or-minus 0.5 mA of 10 milliseconds, and (3) apulse current of plus-or-minus 2 mA of 0.8 nanoseconds.

Read-out was performed by passing a sense current of 0.1 mA, and byreading the voltage.

As a result, in the case of using the conditions of the above (1), theresistance change after writing was not seen and it tuned out that therecoding was not performed.

In the case of using the conditions of the above (2), when minus 0.5 mAwrite-in current Iw was passed first, the resistance was changed from alow resistance state to a high resistance state.

However, even if a writing was tried afterward by using a current pulsewith a reversed polarity, resistance had maintained the high resistancestate. Thus, it turned out that only one way signal writing could becarried out.

In the case of using the conditions of the above (3), it was possible tochange the resistance according to the polarity of write-in current Iw,and thus, “0” signal and “1” signal were able to be written in.

Moreover, it became possible to write-in to the sample which was notwritten-in by using the condition (2) as mentioned above, by passing the0.3 mA pulse current for 10 nanoseconds to the word line which is notshown in the figure. This is due to the assistance of magnetic fieldgenerated by the additional word line.

As explained above, it was confirmed that the magnetic memory of theinvention was suitable for the recordable magnetic memory with lowwriting current.

In addition, there are other methods of choosing a memory cell in themagnetic memory of the invention besides using MOSFETs.

FIG. 51 is a schematic diagram showing the magnetic memory where thediodes are used.

That is, the diode D is connected in series with the magnetic cell 10 ofthe invention near the crossing of the bit line BL and the word line WLwired in a matrix fashion.

In the case of this magnetic memory, a specific memory cell can beaccessed by specifying the word line WL and the bit line BL.

In this case, the diodes D have a role to intercept the currentcomponent which flows other memory cells connected to the selected wordline WL and/or the selected bit line BL.

The Eighteenth Example

Next, the probe access type magnetic memory shown in FIG. 26 will beexplained as the eighteenth example of the invention.

As the example, the magnetic element for recording and reproductionshown in 27 was formed on the substrate.

First, after forming lower wiring on the wafer, the bottom electrode EL2by which common connection is made was formed. And on this wafer, themultilayer film of laminated structure of Ta(5 nm)/Ru(2 nm)/PtMn(15nm)/Co₉Fe₁(15 nm)/Al₂O₃(0.8 nm)/Co₉Fe ₁(2 nm)/Cu(6 nm)/Co₉Fe₁(4 nm)/Ru(1 nm)/Co₉Fe₁(4 nm)/PtMn(15 nm)/Pt (2 nm) was formed.

The mask for cells was formed by applying and heat-treating the polymersof two-phase-sepaaration type to this multilayer film.

Next, a patterned medium can be formed by performing an ion milling.

The ion milling was stopped at the bottom of the magnetic recordinglayer Co₉Fe₁ (2 nm), thus a structure was obtained where theintermediate layer B2 (A₂O₃ (0.8 nm)) and the magnetically fixed layerC2 (Co₉Fe₁ (15 nm)) were shared by a plurality of magnetic cells.

In this structure, since patterning of intermediate layer B2 is notcarried out, a formation of an unexpected current path by re-depositionto the side wall of the intermediate layer B2 can be prevented.Moreover, the homogeneity of cell resistances can be acquired.

Thus, a plurality of magnetic cells with a diameter of about 28 nm wereformed.

Next, by embedding the insulator 100 between the magnetic cells, thestructure shown in FIG. 27 was completed.

To a plurality of magnetic cells 10, a probe 200 is made to scan and anyone of the cells can be chosen by making the probe contact thereto.

First, a signal “1” was written in the cell 1 by passing a plus 0.2 mAcurrent thereto, and a signal “0” was written in the cell 2 by passing aminus 0.2 mA current thereto. Here, the direction of the current whereelectrons flow from the upper (top) electrode to the lower (bottom)electrode is defined to correspond to the polarity of plus.

Furthermore, a signal “1” was written in the cell 3 by passing a plus0.2 mA current thereto, and a signal “0” was written in the cell 4 bypassing a minus 0.2 mA current thereto.

Next, a read-out was performed. That is, resistance of each cell wasinvestigated by passing a sense current of plus 0.03 mA. Consequently,the detected resistances were two-valued and a high resistance, a lowresistance, a high resistance, and a low resistance were observed forthe cell 1 through cell 4, respectively. That is, it was confirmed that“1” or “0” signal was written in each cell.

In addition, when the write-in current was plus-or-minus 0.05 mA, astable signal writing was not made.

As explained above, it was confirmed that the magnetic memory of thisexample was suitable for the recordable magnetic memory with low writingcurrent.

Heretofore, the embodiments of the present invention have beenexplained, referring to the examples.

However, the present invention is not limited to these specificexamples.

For example, the size and material of each element which constitutes themagnetic cell, and the form and the quality of electrodes, passivationand insulated structure may be appropriately selected by those skilledin the art with the known techniques to carry out the invention astaught in the specification and obtain equivalent effects.

Moreover, the antiferromagnetic layer, the magnetically fixed layer, theintermediate layer, the magnetic recording layer, and the insulatinglayer in the magnetic cell may have single layer, or two or more layers.

Further, also concerning the magnetic cell and the magnetic memoryaccording to the invention, those skilled in the art will be able tocarry out the invention appropriately selecting a material or astructure within known techniques.

While the present invention has been disclosed in terms of theembodiment in order to facilitate better understanding thereof, itshould be appreciated that the invention can be embodied in various wayswithout departing from the principle of the invention. Therefore, theinvention should be understood to include all possible embodiments andmodification to the shown embodiments which can be embodied withoutdeparting from the principle of the invention as set forth in theappended claims.

1. A magnetic cell comprising: a first ferromagnetic layer whosemagnetization is substantially fixed in a first direction; a secondferromagnetic layer whose magnetization is substantially fixed in asecond direction opposite to the first direction; a third ferromagneticlayer provided between the first and the second ferromagnetic layers, adirection of magnetization of the third ferromagnetic layer beingvariable; a first intermediate layer provided between the first and thethird ferromagnetic layers; and a second intermediate layer providedbetween the second and the third ferromagnetic layers; the direction ofmagnetization of the third ferromagnetic layer being determined under aninfluence of spin-polarized electrons upon the third ferromagnetic layerby passing a current between the first and the second ferromagneticlayers. 2-23. (canceled)